But Sen. John Ensign , R-Nev., a Finance Committee member who spoke with Geithner Wednesday morning said, “I don’t think I see enough in there to cause a problem.”

While Geithner’s backers called the incidents “honest mistakes,” they clearly could complicate the confirmation of one of Obama’s most important nominees at a time of economic turmoil and just days before the incoming president is set to take office.

Similar incidents have sunk nominations in the past.

“I am disappointed in the errors found in Tim Geithner’s tax returns and other information, but I am satisfied that Mr. Geithner has taken the steps necessary to fix these problems,” Baucus said. “That’s why I intend to move forward as soon as possible with a hearing on his nomination.”

Geithner was quizzed Tuesday behind closed doors by members of the panel.

GOP Sen. Lindsey Graham of South Carolina offered strong support for Geithner at an appearance with Obama. “Now’s not the time to think in small political terms,” Graham advised. “I think he’s the right guy.”

Obama characterized the issue as an “embarrassment” and said he expects the Senate to confirm Geithner.

Vetting Process

During the vetting process, Obama’s transition team and the committee raised questions about the housekeeper’s immigration status. She was not in the country illegally, but her green card for work had lapsed.

Lawmakers are also looking at Geithner’s failure to pay self-employment taxes — the Social Security and Medicare payroll taxes a self-employed person must pay as both an employee and employer — during his time working for the IMF from 2001 to 2004. He paid those after audits in 2006 and vetting in 2008.

As Treasury secretary, Geithner would be in charge of the IRS, which makes his tax problems especially embarrassing.

While several committee members left Tuesday’s meeting without comment, some expressed their support for Geithner. Senate Majority Leader Harry Reid , D-Nev., later said that the flap would not affect his support for Geithner’s confirmation.

“While I do not know Mr. Geithner well, I do understand honest mistakes,” Reid said in a statement. “I continue to believe he has the skills the president will need to confront the challenges of our nation’s economic crisis, and I will support his nomination.”

Orrin G. Hatch , R-Utah, a Finance Committee member, said he still supports Geithner’s nomination, as did Debbie Stabenow , D-Mich., who said Geithner was “forthrightly” answering questions from committee members.

Charles E. Schumer , D-N.Y., also continued to support the nomination. “Tim came to the committee, admitted he had made some mistakes and was very contrite. In my opinion, these mistakes were not at all disqualifying,” Schumer said.

Common Mistake?

Geithner currently serves as president of the Federal Reserve Bank of New York. He has worked closely with outgoing Treasury Secretary Henry M. Paulson Jr. and Federal Reserve Chairman Ben S. Bernanke on efforts to stabilize the financial sector and unfreeze the credit markets.

The Treasury secretary wields enormous power over the banking, auto and insurance industries because of the power granted last him last year in the $700 billion bailout legislation (PL 110-343).

Geithner was Treasury undersecretary for international affairs during the final two years of the Clinton administration. He then worked at the IMF from 2001 to 2003. He earned a small amount from the IMF in 2004.

Geithner’s advocates portrayed his tax missteps as a common mistake for U.S.-based employees of the IMF, who receive W-2 forms even though they are technically treated as self-employed. He was required to file self-employment taxes himself.

A Finance Committee report notes, however, that IMF employees receive several documents explaining how they are supposed to handle this matter. They also receive additional pay designed to compensate them for the taxes they owe.

In 2006, Geithner was audited by the IRS for failing to pay self-employment taxes on IMF income he earned in 2003 and 2004. A Democratic official said an accountant had incorrectly notified Geithner in writing that he was exempt from those taxes. He subsequently paid $16,732 in taxes and interest for those years, according to a memorandum released by Democratic and Republican committee staff members.

For the years 2001 and 2002, an accountant employed by Geithner did not catch the error. The Obama transition team caught the mistake during its vetting process, and Geithner paid $25,970 in back taxes and interest.

On the housekeeper issue, the Democratic official said that Geithner’s family employed the individual from 2004 to 2005 and did not realize that her green card lapsed three months before she stopped working for them. She continued to live legally in the United States and was granted a green card months later, after marrying a U.S. citizen.

Obama’s team issued a strong statement of support for Geithner.

“The president-elect chose Tim Geithner to be his Treasury secretary because he’s the right person to help lead our economic recovery during these challenging times,” Obama spokesman Robert Gibbs said in a statement. “He made a common mistake on his taxes, and was unaware that his part-time housekeeper’s work authorization expired for the last three months of her employment.”

Kathleen Hunter and David Nather contributed to this story.