Italia Federici, an ally of disgraced lobbyist Jack Abramoff, pleaded guilty Friday to tax evasion and obstructing a Senate investigation into the Jack Abramoff lobbying scandal.

Federici's plea was part of a deal with the Justice Department that two people close to the case said could lead investigators to officials in Congress and the Bush administration.

Federici served as a go-between for Abramoff, who currently is in prison, and J. Steven Griles, a deputy Interior secretary who also has pleaded guilty to lying to Senate investigators.

In court Friday, Federici acknowledged lying about this relationship when she testified before the Senate Indian Affairs Committee, which in 2005 was investigating Abramoff's dealings with the Interior Department.

She also admitted supplementing her salary as co-founder of the Council of Republicans for Environmental Advocacy by making ATM withdrawals directly from the organization's bank accounts. Court documents says she did not pay income tax from 2001 through 2003 and owes tens of thousands of dollars in back taxes.

Federici founded the environmental advocacy group with Gale Norton before Norton was named Interior secretary by President Bush in 2001. Also helping start the group was Grover Norquist, a college friend of Abramoff and a close ally of Bush.

Authorities believe Federici may be able to provide information about Norton, other Bush administration officials and the contacts that she, Abramoff and Griles cultivated in Congress, according to two people close to the investigation. Both spoke on condition of anonymity because the investigation is ongoing.