Congress, spurred by national outrage over the Enron scandal, is close this week to approving the first big reform of campaign finance since the 1974 Watergate crisis.
The House of Representatives is due to vote tomorrow on a bill that would ban so-called soft money – massive unregulated contributions from corporations, unions and individuals to the parties, which "launder" them into finance for specific campaigns.
A similar bill has passed the Senate, and backers of the House measure believe that the debacle of Enron, which, in a decade, gave some $6.5m (£4.5m) of "soft money" in return for political access, has made the system indefensible.
The House bill, sponsored by Martin Meehan, a Massachusetts Democrat, and Christopher Shays, a Connecticut Republican, has only come to the floor because a majority of the 435 congressmen signed a petition demanding a vote, in defiance of the wishes of the House Republican leadership. No less a figure than the Speaker, Dennis Hastert, has said passage of the bill would be an "armageddon" for the Republicans and would cost his party control of the House.
Six months ago, such a threat might have been enough. But Enron has created momentum for the measure and made a veto by President George Bush next to impossible. In the 2000 campaign, when Republicans and Democrats collected $458m of "soft money", Mr Bush strongly opposed curbs. But the last thing he wants to do now is attract further attention to the close links between his administration and Enron.
The vote on the bill will come 24 hours after Kenneth Lay, Enron's former chairman and a personal friend of Mr Bush, appears at a Senate hearing. He is likely to refuse to testify.