Last June, with a financial hurricane gathering force, Treasury Secretary Henry M. Paulson Jr. convened the economic stewards of the United States for a brainstorming session. What emergency powers might the government want at its disposal to confront the crisis? he asked.

Timothy F. Geithner, who as president of the New York Federal Reserve Bank oversaw many of the most powerful American financial institutions, stunned the group with the audacity of his answer. He proposed asking Congress to give the president broad power to guarantee all the debt in the banking system, according to two participants, including Michele A. Smith, then an assistant Treasury secretary.

The proposal quickly died amid protests that it was politically untenable because it could put taxpayers on the hook for trillions of dollars.

‘‘People thought, ‘Wow, that’s kind of out there,’ ’’ said John C. Dugan, the U.S.

comptroller of the currency, who heard about the idea afterward.

Mr. Geithner says, ‘‘I don’t remember a serious discussion on that proposal then.’’ But in the 10 months since, the government has in many ways embraced his blue-sky prescription. Step by step, through an array of new programs, the Federal Reserve and Treasury have assumed an unprecedented role in the banking system, using unprecedented amounts of taxpayer money, to try to save the U.S. financiers from their own mistakes.

And more often than not, Mr. Geithner has been a leading architect of those bailouts, the activist at the head of the pack.

He was the U.S. regulator most willing to ‘‘push the envelope,’’ said H. Rodgin Cohen, a prominentWall Street lawyer who spoke frequently with Mr. Geithner.

Today, Mr. Geithner is Treasury secretary, and as he seeks to rebuild the fractured U.S. financial system with more taxpayer assistance and a regulatory overhaul, he finds himself a locus of discontent.

Even as banks complain that the government has attached too many intrusive strings to its financial assistance, a range of critics — lawmakers, economists and even former Federal Reserve colleagues — say that the bailout Mr.

Geithner has played such a central role in fashioning is overly generous to the financial industry at taxpayers’ expense.

An examination of Mr. Geithner’s five years as president of the NewYork Fed, an era of unbridled and ultimately disastrous risk-taking by the financial industry, shows that he forged unusually close relationships with executives of Wall Street’s giant financial institutions.

His actions, as a regulator and later a bailout king, often aligned with the industry’s interests and desires, according to interviews with financiers, regulators and analysts and a review of Federal Reserve records.

In a pair of recent interviews and an exchange of e-mail messages, Mr.

Geithner defended his record, saying that from very early on, he was ‘‘a consistently dark voice about the potential risks ahead, and a principal source of initiatives designed to make the system stronger’’ before the markets collapsed.

Mr. Geithner said his actions in the bailoutwere motivated solely by a desire to help businesses and consumers. But in a financial crisis, he added, ‘‘the government has to take risk, and we are going to be doing things which ultimately —in order to get the credit flowing again — are going to benefit the institutions that are at the core of the problem.’’ The New York Fed is, by custom and design, clubby and opaque. It is charged with curbing banks’ risky impulses, yet its president is selected by and reports to a board dominated by the chief executives of some of those same banks. Traditionally, the NewYork Fed president’s intelligence-gathering role has involved routine consultation with financiers, though Mr. Geithner’s recent predecessors generally did not meet them unless senior aides were also present, according to the bank’s former general counsel.

By those standards, Mr. Geithner’s reliance on bankers, hedge fund managers and others to assess the market’s health — and provide guidance once it faltered—stood out. His calendars from 2007 and 2008 show that those interactions wereamix of the professional and the private.

He ate lunch with senior executives from Citigroup, Goldman Sachs and Morgan Stanley at a restaurant in the Four Seasons Hotel or in their corporate dining rooms. He attended casual dinners at the homes of executives like Jamie Dimon, amemberof theNewYork Fed board and the chief of JPMorgan Chase.

Mr. Geithner was particularly close to executives of Citigroup, the largest bank under his supervision. Robert E.

Rubin, a senior Citigroup executive and a former Treasury secretary, was Mr.

Geithner’s mentor from his years in the Clinton administration, and the two kept in close touch in New York.

Mr.Geithner met frequently with Sanford I. Weill, one of Citigroup’s largest individual shareholders and its former chairman, serving on the board of a charity Mr. Weill led. As the bank was entering a financial tailspin, Mr. Weill approached Mr. Geithner about taking over as Citigroup’s chief executive.

But for all his ties to Citigroup, Mr.

Geithner repeatedly missed or overlooked signs that the bank—along with the rest of the financial system — was falling apart. When he did spot trouble, analysts say, his responses were too measured, or too late.

In 2005, for instance, Mr. Geithner raised questions about how well Wall Street was tracking its trading of complex financial products known as derivatives, yet he pressed for changes only at the margins. Problems with the risky and opaque derivatives market later amplified the economic crisis.

In fashioning the bailout, his drive to use taxpayer money to backstop faltering firms overrode concerns that such a strategy would encourage more risktaking in the future. In one bailout instance, Mr. Geithner fought a proposal to levy fees on banks that would help protect taxpayers against losses.

To Joseph E. Stiglitz, a Nobel-winning economist at Columbia University and a critic of the bailout, Mr. Geithner’s actions suggest that he came to share Wall Street’s regulatory philosophy and world view.

‘‘I don’t think that Tim Geithner was motivated by anything other than concern to get the financial system working again,’’ Mr. Stiglitz said. ‘‘But I think that mind-sets can be shaped by people you associate with, and you come to think that what’s good for Wall Street is good for America.’’ In this case, he added, that ‘‘led to a bailout that was designed to try to get a lot of money to Wall Street, to share the largesse with other market participants, but that had deeply obvious flaws in that it put at risk the American taxpayer unnecessarily.’’ But Ben S. Bernanke, the chairman of the Federal Reserve, said in an interview that Mr. Geithner’s Wall Street relationships made him ‘‘invaluable’’ as they worked together to steer the country through crisis.

‘‘He spoke frequently to many, many different players and kept his finger on the pulse of the situation,’’ Mr.

Bernanke said. ‘‘He was the point person formein many cases and with many individual firms so that we were prepared for any kind of emergency.’’

AN ALTERNATE PATH

A revolving door has long connected Wall Street and the New York Fed. Mr.

Geithner’s predecessors, E. Gerald Corrigan and William J. McDonough, wound up as investment-bank executives.

The current president, William C.

Dudley, came from Goldman Sachs.

Mr. Geithner followed a different route. An expert in international finance, he served under both Clinton-era Treasury secretaries,Mr. Rubin andLawrence H. Summers. He impressed them with his handling of foreign financial crises in the late 1990s before landing a top job at the International Monetary Fund.

When the New York Fed was looking for a new president, both former secretaries were advisers to the bank’s search committee and supportedMr.Geithner’s candidacy. Mr. Rubin’s seal of approval carried particular weight because he was by then a senior official at Citigroup.

At the New York Fed, top executives of global financial giants fill many seats on the board. In recent years, board members have included the chief executives of Citigroup and JPMorgan Chase, as well as top officials of Lehman Brothers and industrial companies like General Electric.

In theory, having financiers on the New York Fed’s board should help the president be Washington’s eyes and ears on Wall Street. But critics, including some current and former Federal Reserve officials, say the New York Fed is often more of a Wall Street mouthpiece than a cop.

Willem H. Buiter, a professor at the London School of Economics and Political Science who caused a stir at a Fed retreat last year with a paper concluding that the Federal Reserve had been co-opted by the financial industry, said the structure ensured that ‘‘Wall Street gets what it wants’’ in its New York president: ‘‘A safe pair of hands, someone who is bright, intelligent, hardworking, but not someone who intends to reform the system root and branch.’’ Mr. Geithner took office during one of the headiest bull markets ever. Yet his most important task, he said in an interview, was to prepare banks for ‘‘the storm that we thought was going to come.’’ In his first speech as president in March 2004, he advised bankers to ‘‘build a sufficient cushion against adversity.’’ Early on, he also spoke frequently about the risk posed by the explosion of derivatives, unregulated insurancelike products that many companies use to hedge their bets.

But Mr. Geithner acknowledges that ‘‘even with all the things that we took the initiative to do, I didn’t think we achieved enough.’’ Mr. Geithner pushed the industry to keep better records of derivative deals, a measure that experts credit with mitigating the chaos once firms began to topple.

But he stopped short of pressing for comprehensive regulation and disclosure of derivatives trading and even publicly endorsed their potential to damp risk.

Mr. Geithner said many of the New York Fed’s supervisory actions could not be disclosed because of confidentiality issues. As a result, he added, ‘‘I realize I am vulnerable to a different narrative in that context.’’ The ultimate tool atMr.Geithner’s disposal for reining in unsafe practices was to recommend that the Board of Governors of the Fed publicly rebuke a bank with penalties or cease-and-desist orders.

On his watch, only three such actions were taken against big American banks — none after 2006, when banks’ lending practices were at their worst.

THE CITIGROUP CHALLENGE

Perhaps the central regulatory challenge for Mr. Geithner was Citigroup.

Cobbled together by Mr. Weill through a series of pell-mell acquisitions into the world’s largest bank, Citigroup reached into every corner of the financial world: credit cards, auto loans, trading, investment banking, as well as mortgage securities and derivatives.

But it was plagued by mismanagement and wayward banking practices.

In 2004, the NewYork Fed levied a $70 million penalty against Citigroup over the bank’s lending practices. The next year, the New York Fed barred Citigroup from further acquisitions after the bank was involved in trading irregularities and questions about its operations.

The New York Fed lifted that restriction in 2006, citing the company’s ‘‘significant progress’’ in carrying out risk-control measures.

In fact, risk was rising to dangerous levels at Citigroup as the bank dove deeper into mortgage-backed securities.

Throughout the spring and summer of 2007, as subprime lenders began to fail and government officials reassured the public that the problems were contained, Mr. Geithner met repeatedly with members of Citigroup’s management, records show.

From mid-May to mid-June alone, he met at a breakfast meeting Charles O.

Prince 3rd, Citigroup’s chief executive at the time, went to Citigroup’s headquarters in New York to meet Lewis B. Kaden, the company’s vice chairman, and had coffee with Thomas G. Maheras, who ran some of the bank’s biggest trading operations.

(Mr. Maheras’s unit would later be roundly criticized for taking many of the risks that led Citigroup aground.) His calendar shows that during that period he also had breakfast with Mr.

Rubin. But in his conversations with Mr.

Rubin, Mr. Geithner said, he did not discuss bank matters. ‘‘I did not do supervision with Bob Rubin,’’ he said.

Any intelligence Mr. Geithner gathered in his meetings does not appear to have prepared him for the severity of the problems at Citigroup and beyond.

InaMay 15, 2007, speech to the Federal Reserve Bank of Atlanta,Mr.Geithner praised the strength of the top U.S. financial institutions, saying that innovations like derivatives had ‘‘improved the capacity to measure and manage risk’’ and declaring that ‘‘the larger global financial institutions are generally stronger in terms of capital relative to risk.’’ Two days later, interviews and records show, he lobbied behind the scenes for a plan that a government study said could lead banks to reduce the amount of capital they kept on hand.

While waiting for a breakfast meeting with Mr. Weill at the Four Seasons in New York, Mr. Geithner phoned Mr.

Dugan, the comptroller of the currency, according to both men’s calendars. Both Citigroup and JPMorgan Chase were pushing for the new standards, which they said would make them more competitive.

Records show that earlier that week,Mr.Geithner had discussed the issue with JPMorgan’s chief, Mr. Dimon.

At the Federal Deposit Insurance Corp., which insures bank deposits, the chairwoman, Sheila C. Bair, argued that the new standards were tantamount to letting the banks set their own capital levels. Taxpayers, she warned, could be left ‘‘holding the bag’’ in a downturn.

But Mr. Geithner believed that the standards would make the banks more sensitive to risk, Mr. Dugan recalled. The standards were adopted but have yet to go into effect.

By the fall of 2007, that was becoming clear. Citigroup alone would eventually require $45 billion in direct U.S. taxpayer assistance to stay afloat.

On Nov. 5, 2007, Mr. Prince stepped down as Citigroup’s chief in the wake of multibillion-dollar mortgage writedowns.

Mr. Rubin was named chairman, and the search for a new chief executive began. Mr. Weill had a perfect candidate: Mr. Geithner.

OnNov. 6 and 7, 2007, asMr.Geithner’s bank examiners scrambled to assess Citigroup’s problems, he and Mr. Weill spoke twice, records show, once for a half-hour on the phone and once for an hourlong meeting in Mr. Weill’s office, followed by a National Academy Foundation cocktail reception. Mr. Geithner also went to Citigroup headquarters for a lunch with Mr. Rubin on Nov. 16 and met Mr. Prince on Dec. 4, records show.

Mr. Geithner acknowledged that Mr.

Weill had spoken with him about the Citigroup job. But he immediately rejected the idea, he said, because he did not think he was right for the job.

According to New York Fed officials, Mr. Geithner informed the reserve bank’s lawyers about the exchange with Mr. Weill, and they told him to recuse himself from Citigroup business until the matter was resolved.

Mr. Geithner said he ‘‘would never put myself in a position where my actions were influenced by a personal relationship.’’

COPING WITH CRISIS

AsMr. Geithner sees it, most of the institutions hit hardest by the crisis were not under his jurisdiction — some were foreign banks, mortgage companies and brokerage firms. But he acknowledges that ‘‘the thing I feel somewhat burdened by is that I didn’t attempt to try to change the rules of the game on capital requirements early on,’’ which could have left banks in better shape to weather the storm.

By last autumn, it was too late. The government, with Mr. Geithner playing a lead role alongside Mr. Bernanke and Mr. Paulson, scurried to rescue the financial system from collapse. As the Fed became the biggest vehicle for the bailout, its balance sheet more than doubled, from $900 billion in October 2007 to more than $2 trillion today.

‘‘I couldn’t have cared less about Wall Street, but we faced a crisis that was going to cause enormous damage to the economy,’’ Mr. Geithner said.

The first to fall was Bear Stearns, which had bet heavily on mortgages and by mid-March was tottering. Mr.

Geithner and Mr. Paulson persuaded JPMorgan Chase to take over Bear. But to complete the deal, JPMorgan insisted that the government buy $29 billion in risky securities owned by Bear.

Some officials at the Federal Reserve feared encouraging risky behavior by bailing out an investment house that did not even fall under its umbrella. To Mr.

Geithner’s supporters, that he prevailed in the case of Bear and other bailout decisions is testament to his leadership.

‘‘He was a leader in trying to come up with an aggressive set of policies so that it wouldn’t get completely out of control,’’ said Philipp Hildebrand, a top official at the Swiss National Bank who has worked with Mr. Geithner to coordinate an international response to the worldwide financial crisis.

But others are less enthusiastic. William Poole, president of the Federal Reserve Bank of St. Louis until March 2008, said that the Fed, by effectively creating money out of thin air, not only runs the risk of ‘‘massive inflation’’ but also has done an end-run around Congressional power to control spending.

Mr. Geithner played a pivotal role in the next bailout, which was even bigger — that of the American International Group, the insurance giant whose derivatives business had brought it to the brink of collapse in September. He also went to bat for Goldman Sachs, one of the insurer’s biggest trading partners.

As A.I.G. bordered on bankruptcy,Mr.

Geithner pressed first for a private sector solution. A.I.G. needed $60 billion to meet payments on insurance contracts it had written to protect customers against debt defaults.

A.I.G.’s chief executive at the time, Robert B. Willumstad, said he had hired bankers at JPMorgan to help it raise capital.Goldman Sachs had jockeyed for the job as well, but because the investment bank was one of A.I.G.’s biggest trading partners, Mr. Willumstad rejected the idea. The potential conflicts of interest, he believed, were too great.

Nevertheless, on Monday, Sept. 15, Mr. Geithner pushed A.I.G. to bring Goldman onto its team to raise capital, Mr. Willumstad said.

A Goldman spokesman said, ‘‘We don’t believe anyone at Goldman Sachs asked Mr. Geithner to include the firm in the assignment.’’ Mr. Geithner said he had suggested Goldman get involved because the situation was chaotic and ‘‘time was running out.’’ But A.I.G.’s search for capital was fruitless. The government would step in with an $85 billion loan, the first installment of a bailout that nowstands at $182 billion. As part of the bailout, A.I.G.’s trading partners, including Goldman, were compensated fully for money owed to them by A.I.G.

RESCUES REVISITED

As Mr. Geithner runs the Treasury and administration officials signal more bailout moneymay be needed, the specter of bailouts past haunts his efforts.

He recently weathered a firestorm over retention payments to A.I.G. executives made possible in part by language inserted in the administration’s stimulus package at the Treasury Department’s insistence. And his new efforts to restart the financial industry suggest the same philosophy that guided Mr. Geithner’s Fed years.

According to a recent report by the inspector general monitoring the bailout, Neil M. Barofsky, Mr. Geithner’s plan to underwrite investors willing to buy the risky mortgage-backed securities still weighing down banks’ books is a boon for private equity and hedge funds but exposes taxpayers to ‘‘potential unfairness’’ by shifting the burden to them.

One year and two administrations into the bailout, Mr. Geithner is perhaps the single person most identified with the enormous checks the government has written. At every turn, he is being second-guessed about the rescues’ costs and results. But he remains firm in his belief that failure to act would have been much more costly.