WASHINGTON — When the Senate returns next week, lawmakers will have to decide whether to raise taxes on hedge-fund managers and corporations to prevent a tax hike for 23 million Americans. The chamber has dawdled on an $80 billion measure penned by Rep. Charles Rangel of Harlem aimed at providing a one-year fix of the alternative minimum tax, which could hit millions in the middle class even though it was meant to affect only the wealthiest taxpayers. The holdup has led the Internal Revenue Service to chastise lawmakers, most recently on Monday when the chairman of the agency’s oversight board informed two senior senators that officials were “gravely concerned” that congressional inaction on the AMT could drive up costs and delay the receipt of taxpayer refunds. The House passed the bill on a party line vote earlier this month, but the Senate left for the Thanksgiving recess without acting on it. Congressional aides report little progress over the break to end the stalemate.

The central point of dispute has not changed: Many Democrats want to offset the cost of fixing the minimum tax by raising rates elsewhere, while Republicans and the Bush administration say the so-called “patch” should not be paid for with tax increases.

The House bill includes a hotly contested provision that would more than double the tax rate imposed on the “carried interest” profits earned by the managers of hedge funds and private equity firms, along with other measures that eliminate certain tax advantages for corporations.

Amid an aggressive lobbying effort by the private equity industry, some Democrats, including Senator Schumer, are cool to the carried interest provision. In an effort to smooth passage of the AMT legislation, the chairman of the Senate Finance Committee, Senator Baucus of Montana, tried to strip the carried interest tax hike from the bill shortly before lawmakers left town for Thanksgiving.

Aides and industry sources now say the carried interest measure is all but dead, although the majority leader, Senator Reid of Nevada, refuses to rule it out. “Nothing is on or off the table,” a spokesman for the leader, Jim Manley, said. “Senator Reid is committed to paying for AMT relief, but the Republicans have made it clear that they are not.”

He said Mr. Reid hoped to work with Republicans when the session resumes next week and that he wanted to pass legislation “as quickly as possible.”

Under the amendment offered by Mr. Baucus, the bill would be partially but not completely, paid for by eliminating some tax breaks for corporations and by raising rates for private equity firms that go public, a measure that is also opposed by some in the industry but has broader support in Congress.

The issue has put Democrats in a bind. Republicans have already labeled their proposal a tax increase, but if they strip out the offsets, they will have to waive “pay as you go” rules they enacted upon taking control of Congress in January that require any tax cuts to be balanced by tax increases elsewhere in the code. The changes were aimed at restoring fiscal responsibility Democrats said had been absent from the Republican-led Congress. The bill also extends several popular tax breaks.

The Democratic presidential candidates in the Senate have been quiet on the legislation, waiting to see what a final bill looks like before taking a firm position. Senator Clinton has said she supports reforming the AMT as well as raising the tax rate on carried interest, but she has not said whether she supports the bill that passed the House. Her Senate spokesman did not return multiple requests for comment on the legislation this week.

A spokeswoman for Senator Obama of Illinois said only that he “supports a fiscally responsible fix to the problems with the AMT” and would look carefully at legislation the Senate considers.

For Mrs. Clinton, the issue could force her to take sides between two home state allies. Mr. Rangel, the chairman of the House Ways and Means Committee, has pushed aggressively for an AMT bill that is fully paid for, including the carried interest provision, while Mr. Schumer has resisted the measure passed by the House and may be in the camp willing to waive the “pay as you go” rules.

Republicans, meanwhile, are watching to see where Mrs. Clinton comes down. “Hillary Clinton told the American people that she would reform the AMT but refuses to explain how she plans to do it,” a spokesman for the Republican National Committee, Danny Diaz, said. “This is a problem that is not going to disappear, and taxpayers expect leaders to tackle tough issues, not dodge them.”