Another Cabinet nomination by President Barack Obama is running into tax problems that could impede his confirmation.
Senate Democratic majority leader Tom Daschle failed to pay more than $US128,000 in taxes.
He has been nominated as Secretary of Health & Human Services.
Mr Daschle recently filed amended tax returns to pay back taxes, interest and penalties involving unreported consulting income, charitable contributions and use of a car service provided by a prominent businessman and Democratic donor.
The White House acknowledged in a statement on Friday night that "some tax issues" had emerged during his nomination process.
Treasury Secretary Timothy Geithner's nomination was held up earlier by criticism over late payment of $US34,000 in taxes.
Mr Obama has vowing sweeping change in the way Washington operates, including accountability.
Despite the disclosure, the White House says the president expects Mr Daschle will still be confirmed by the Senate.
A meeting of the Senate Finance Committee has been called for Monday to discuss pending nominations.
Nomination withdrawn
Mr Obama's original choice for commerce secretary, New Mexico Governor Bill Richardson, withdrew his name in early January.
An investigation is being held into whether a financial company won contracts to advise the state government as a result of donations to his campaign.
