The agreement would also:

– Extend unemployment benefits for 2 million Americans.

– Prevent about 30 million Americans from having to pay the alternative minimum tax.

– Keep Medicare payments to doctors at the current rate.

– Extend of tax credits for children and college tuition.

– Provide tax breaks to clean-energy companies.

– Raise the estate tax, but significantly less than Democrats had wanted. The value of estates over $5 million would be taxed at 40 percent, up from 35 percent.

– Taxes on capital gains and dividends would remain the same, 15 percent, for most Americans, but they would climb to 20 percent for top earners.

The bargain includes significant concessions by Democrats and Republicans, though perhaps more for the GOP, which had been against any tax increase. The compromise’s future remained in doubt with both members of both parties publicly criticizing the deal.

Sen. Tom Harkin, D-Iowa, said he was disappointed that Democrats were abandoning their promise to extend only those Bush-era tax cuts on individual income below $200,000 and family income below $250,000. Republicans had been pushing to extend all of the tax cuts.

“The direction they’re headed is just absolutely the wrong direction for our country,” he said. “As I see this thing developing – quite frankly, as I’ve said before – no deal is better than a bad deal, and this looks like a very bad deal, the way this is shaping up.”

Progressive groups, including the AFL-CIO and MoveOn.org, lobbied Democrats to vote against the compromise.

“The public is paying attention, and we urge all Democrats to stand on principle at this moment,” the Progressive Change Campaign Committee wrote in a statement. “The current deal violates progressive principles. It should be opposed.”

But Sen. Rand Paul, R-Ky., urged Democrats and the White House to stop picking on wealthy earners and implored his congressional colleagues not to vote for a measure that raises taxes, though a failure to act would ensure broad tax increases.

“The Republican Party should have no fingerprints on this and in no way support anything that raises taxes because it’s bad economic policy,” Paul said.

At a campaign-style event at the Old Executive Office Building across the street from the White House, Obama urged Congress to pass a bill as soon as possible to protect middle-class taxpayers.

“Preventing that tax hike has been my top priority, because the last thing folks like the folks up here on this stage can afford right now is to pay an extra $2,000 in taxes next year,” he said in an auditorium with a group of cheering people behind him and in the audience. “Middle-class families can’t afford it. Businesses can’t afford it. Our economy can’t afford it.”

The White House refused to identify any of the people or say how it knew they were in the middle class.

“I know the president has fun heckling Congress,” said Sen. Bob Corker, R-Tenn. “It’s unfortunate that he doesn’t spend as much time working on solving problems as he does with campaigns and pep rallies.”

If a deal fails, Sen. Joe Manchin, D-W.Va., introduced a bill – the Cliff Alleviation at the Last Minute – that would phase in the looming tax increases over three years, rather than all at once, and allow the Office of Management and Budget to pick which programs would be cut rather than having the across-the-board cuts contained in sequestration.

“This is not a great plan, merely a better plan than going over the cliff,” Manchin said in a floor speech. “It should never have come to this.”

Lesley Clark, Kevin G. Hall and David Lightman contributed.

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