The Senate is poised to decide whether lawmakers must disclose more about their efforts to fund pet projects and raise money from lobbyists, a move that reform groups say is overdue.
Senate leaders said they hoped to win a showdown vote Thursday morning to end debate and ready the bill for final passage later in the day.
Some conservative Republicans said the bill didn't go far enough, but they appeared glum late Wednesday about their hopes of blocking it. Senate approval would send the measure to President Bush for his signature, because the House overwhelmingly passed it Tuesday.
The Democratic-drafted legislation is a response to recent scandals that sent two GOP lawmakers and a prominent lobbyist to prison, and saw a House Democrat charged with bribery.
It would require lawmakers to disclose those lobbyists who raise $15,000 or more for them within a six-month period by "bundling" donations from many people. Lawmakers seeking targeted spending projects, known as "earmarks" on Capitol Hill, would have to publicize their plans in advance, although critics say the disclosure requirements are hardly airtight.
Gifts from lobbyists or their clients would be banned. Former senators would have to wait two years before lobbying Congress; ex-House members would have to wait one year.
Senators will vote three days after federal agents searched the Alaska home of longtime Sen. Ted Stevens, R-Alaska, as part of a probe into alleged influence-peddling.