Lawyers for Republican lobbyist Jack Abramoff are in discussions with the Justice Department about his possible cooperation in a congressional corruption probe, a person involved in the investigation said Tuesday night.

The probe involves a number of members of Congress as well as staff. A former aide to ex-House Majority Leader Tom DeLay, R-Texas, has already pleaded guilty.

Abramoff would plead guilty under an arrangement that would settle a criminal case against him in Florida as well as potential corruption charges in Washington, said the person, who spoke on condition of anonymity because of the sensitivity of the talks.

The person describing the ongoing discussions said they have been going on "a long time, months." Only in the past week or so have they come "close to any kind of fruition," the person said.

The person cautioned that unspecified issues remain to be worked out. The person added that if the conversations proceeded smoothly, an agreement could be reached quickly, as early as "the beginning of next week." Abramoff has not been charged in the corruption investigation.

The New York Times first reported on the talks Tuesday night in a story its Web site.

The person declined to specify how many members of Congress Abramoff could implicate, saying only that "cooperation is cooperation; it's full cooperation."

Abramoff and his partner, Michael Scanlon, collected over $80 million from Indian tribes to lobby Congress on casino gambling and other issues. The Justice Department is investigating whether trips, gifts and campaign donations arranged by Abramoff were in exchange for official acts by members of Congress, and whether the tribes were defrauded.

In recent days, members of Congress who accepted campaign donations from Abramoff's clients have begun returning the money as the investigation ratchets up in intensity.

Among those returning the most money is Sen. Conrad Burns, R-Mont., for an estimated $150,000.

On Tuesday night, Abramoff's attorney, Abbe Lowell, declined to comment, as did Justice Department spokesman Brian Roehrakasse.

In the Florida case, Abramoff is scheduled to go on trial Jan. 9. He and a former business partner were indicted last summer on charges of conspiracy and fraud. They allegedly concocted a fake $23 million wire transfer to make it appear they were putting a significant portion of their own money in the 2000 purchase of a fleet of gambling boats.

The ex-business partner, Adam Kidan, pleaded guilty last week and agreed to testify against Abramoff, putting pressure on the Washington lobbyist to reach a settlement to reduce his potential prison term.