As Mr. Abramoff entered guilty pleas on conspiracy, fraud and tax evasion charges in a federal court in Washington, and later in a Florida court, shockwaves were spreading through Congress.

In the months leading up to Mr. Abramoff's court appearances, lawmakers were bracing for the impact, and some two dozen had returned money they had received from the former lobbyist or his clients, who included Native American groups.

Among the latest to do so was Republican House Speaker, Dennis Hastert, who announced he would donate $69,000 received from Mr. Abramoff to charity.

Similar announcements came from the former House Majority Leader, Tom DeLay, and Congressman Roy Blunt, the Republican acting as temporary House leader while Mr. DeLay fights criminal charges related to campaign financing.

Republican Congressman Bob Ney, who is among at least half a dozen, but possibly as many as 20 members of Congress believed to be the focus of the federal corruption probe, also announced he would return funds.

Also on Wednesday, President Bush's 2004 re-election campaign announced it is donating to charity $6,000 in contributions connected to Mr. Abramoff.

In announcing that decision, White House Spokesman Scott McClellan stressed that Mr. Abramoff's activities touched on Democrats as well as Republicans.

"I think we are taking the appropriate steps in terms of this individual, [it is] similar to what we have done with previous individuals that may have been involved in wrongdoing that have contributed money too," he said. "And I think in terms of others making those decisions, it is up to them, but there are certainly people on both sides of the [political] aisle that ought to take a look at that."

The federal corruption probe involving Mr. Abramoff has sparked calls in both chambers of Congress for a new push to reform laws relating to lobbying.

Efforts have been underway in the Senate and in the House to do just that. Speaking in a telephone news conference, Democratic Senator Russ Feingold says lawmakers were aware for some time that the Abramoff affair would highlight the need for changes.

"It is typically the shame factor or the fear factor [when] members of Congress realize that this is hurting their reputation that often leads people to be willing to change thestatus quo, so I think it will of course put some wind in our sails and help us get the reform that is needed," he said.

In addition to the federal probe into Mr. Abramoff's activities, Senator John McCain has been leading an investigation in a Senate committee looking at activities involving Native American tribes.

The Abramoff guilty pleas have re-focused attention on mechanisms Congress has to deal with corruption by lawmakers.

However, the House of Representatives Ethics Committee has been virtually paralyzed over the past year amid political battles over procedures, and it is unclear how the equivalent committee in the Senate will deal withreverberationsfrom the Abramoff matter.

With Republicans who control Congress worried about the longer-term effects of the scandal leading to mid-term elections next November, the biggest political impact may be felt in the House, which returns to work a few weeks from now.

There, Republicans must decide whether to hold a new leadership election that would formally replace Congressman DeLay whose legal troubles in Texas, and questions raised in the Abramoff investigation, could effectively rule out his return to power in Washington.