Jack Abramoff (right) with his lawyer (2004 file photo)

High-powered U.S. lobbyist Jack Abramoff has pleaded guilty to fraud and tax evasion charges, clearing the way for him to cooperate with a federal corruption probe that could implicate several top members of Congress.

Abramoff is implicated in two separate investigations. He is accused of defrauding two lenders in Florida in a deal to buy a cruise line, and he is being investigated in Washington for offering trips and other gifts to lawmakers, including former House Majority Leader Tom DeLay.

As part of his plea-bargain, he is expected to cooperate with federal investigators, meaning he could provide names of U.S. congressmen with whom he had illegal dealings. The Associated Press reports the federal probe is focusing on as many as 20 lawmakers and aides.

A number of lawmakers have tried to cut ties with Abramoff in recent weeks by returning his campaign contributions.