As Congress prepared to open hearings Tuesday into Toyota’s safety problems, government regulatory groups

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were questioning whether the deep financial and personal connections between lawmakers and the carmaker could taint the inquiries.

Toyota, as both a major employer in the United States and a major lobbying force in Washington, has staked out a position in the capital unlike that of almost any other non-U.S. corporation, with close ties to a number of the lawmakers who will lead inquiries into the safety defects that have led to the recall of more than eight million vehicles.

U.S. government disclosure records show that Toyota, with 31 lobbyists in Washington last year, has spent nearly $25 million on regulatory and legislative lobbying in the past five years, far more than any other foreign carmaker.

‘‘Toyota has lobbied to a degree that no other foreign automaker has,’’ said Dave Levinthal, communications director for the Center for Responsive Politics, a research group.

‘‘They’ve built up years’worth of connections with federal lawmakers, and that counts for something, when you knowthe people who are waiting for you on the other side of that door in a contentious situation,’’ he said. ‘‘Now, does that mean they’re going to get off easily? That remains to be seen.’’ However, the potential for conflicts of interest is significant, he added.

Toyota’s registered lobbyists include at least eight former officials from Congress and the executive branch. The company also employs former engineers and officials from the National Highway Traffic Safety Administration, the U.S. regulatory agency faulted by some critics for failing to spot a pattern of safety problems at Toyota.

A number of lawmakers have personal financial ties to Toyota as well. More than a dozen members of Congress have owned stock in Toyota since 2008, valued, in some cases, at tens of thousands of dollars. Representative Jane Harman, a California Democrat, led the way, with Toyota stock valued at $116,000 to $315,000 in the most recent congressional disclosure report, which give values in ranges instead of exact figures.

Ms. Harman serves on the House of Representatives Energy and Commerce Committee, which was to begin a public examination of Toyota’s problems at a hearing Tuesday.

On Wednesday, the House oversight committee will hold a hearing of its own on Toyota. The ranking Republican on the committee, Representative Darrell Issa of California, has pressed Toyota for a fuller accounting of the safety problems, but he also has a history of financial connections with carmakers.

Mr. Issa is one of the wealthiest members of Congress with reported assets of as much as $337 million, in his most recent congressional filing. He made his money in the auto-alarm business, selling the Viper alarm and other brands for Toyotas and many other makes. Although he sold his financial interests in the company he founded a decade ago, he remains on its board.

A third congressional panel examining Toyota, the Senate Committee on Commerce, Science, & Transportation, will hold a hearing next week, and its chairman, Senator John D. Rockefeller IV, Democrat of West Virginia, has extensive ties to Toyota as well.

Mr. Rockefeller helped Toyota establish one of its fastest-growing plants in West Virginia, and the company honored him for his support with a lavish dinner in 2008. At the time, he said he was proud to call Toyota a friend and added, ‘‘Weboast of the 1,500 jobs and more than $1 billion in investment they’ve brought us.’’ An estimated 172,000 people in the United States work at Toyota plants, dealerships and suppliers. With a steady stream of damaging articles in recent weeks about Toyota’s years of knowledge of safety problems, supporters say the company’s employment record should earn it a fair and evenhanded review by federal officials.

‘‘Toyota has unquestionably placed the safety of its customers above profits,’’ Governor Steve Beshear of Kentucky, which is home to a Toyota manufacturing plant, said in a letter to Congress this month that was signed by three other governors.

Clarence Ditlow, executive director of the Center for Auto Safety, a consumer group that has examined Toyota’s safety record, said he hoped that members of Congress would be able to set aside their connections to Toyota and undertake the kind of tough examination conducted a decade ago concerning the safety of Ford vehicles and Firestone tires.