WASHINGTON – The White House and key lawmakers cleared the way Thursday night for swift Senate action to avert a Jan. 1 spike in income taxes for nearly all Americans, agreeing to extend breaks for ethanol and other forms of alternative energy as part of the deal.

Tax provisions aimed at increasing production of hybrid automobiles, biodiesel fuel, energy-efficient homes, coal and energy-efficient household appliances would be extended through the end of 2011 under the bill.

Debate on the expanded measure began almost immediately. While there is no precise timetable for passage, a test vote set for Monday afternoon appears likely to demonstrate overwhelming support for the legislation, which supporters say would help accelerate a sluggish recovery from recession.

The events unfolded as the White House predicted that the agreement between President Obama and top Republicans would clear by year’s end — even though House Democrats voted Thursday not to allow it to reach the floor without changes to scale back tax relief for the rich.

“If it’s take it or leave it, we’ll leave it,” Rep. Lloyd Doggett, D-Texas, said after a closed-door meeting in which rank-and-file Democrats chanted: “Just say no.”

“The deal will get passed,” said presidential press secretary Robert Gibbs. There were no predictions to the contrary among senior Democrats on either side of the Capitol.

As announced by Obama, the deal would extend tax breaks at all income levels that are due to expire Jan. 1, renew a program of jobless benefits for the long-term unemployed that is due to lapse within days, and implement a one-year cut in Social Security taxes.

At the insistence of Republicans, it also includes a more generous estate tax provision. That, in turn, infuriated Democrats already unhappy with Obama for agreeing to extend personal tax cuts at incomes over $200,000 for individuals and $250,000 for couples.

The two-year cost of the plan, estimated at about $850 billion, would further swell record federal deficits.

Despite significant criticism from fellow Democrats, Obama has said the sweeping measure is necessary to help the struggling economy recover from the worst recession in decades. With unemployment at 9.8 percent, a top White House official warned Democratic critics Tuesday that they risk sending the economy back into recession if they block the measure.

In the Senate, the emergence of bipartisan legislation also indicated progress for the White House and Senate Majority Leader Harry Reid, D-Nev., toward possible year-end passage of other major items on their agenda.

Obama has made ratification of a new arms control treaty with Russia a top priority. The White House is also pressing Reid to try once more to end the Pentagon’s 17-year ban on openly gay members of the military.

Republicans have vowed to block action on all legislation until a tax bill and a year-end government spending bill have been resolved.

Senate Republican leader Mitch McConnell has said he expects most of his rank and file to support the huge tax bill. Prominent House Republicans back it, too, although they have generally refrained from speaking out at a time when doing so would divert attention from the spectacle of Obama at odds with lawmakers of his own party.

Rep. John Boehner of Ohio, in line to become House speaker when Republicans take power in January, “supports the framework as agreed to by” Obama and McConnell and spoke with the president about it over the weekend, a spokesman said Thursday.

Rep. Paul Ryan of Wisconsin, whose views on economic issues are influential among House Republicans, also swung behind it. “While I have concerns with some specific aspects of the plan, I support the proposed framework to avert further economic hardship and provide a first step to restore the foundations for sustained growth and job creation,” he said in an interview.

Among the energy tax provisions added was an extension of the current 45-cents-per-gallon subsidy for ethanol, at a cost to the Treasury estimated at nearly $5 billion. The issue is of particular interest to lawmakers from Midwestern states with grain crops.

The changes did nothing to ease the opposition among some critics, though. Liberal Sen. Bernie Sanders, I-Vt., attacked the measure’s tax breaks for the wealthy as a threat to the middle class.