WASHINGTON - The political fight to keep the United States out of default on its financial obligations turned Wednesday to a resurrected bipartisan plan in the Senate, the broad outlines of the deal supported by President Barack Obama because it meets his conditions of spending cuts combined with increased tax revenue.

Because such a complex measure might not be ready for congressional action by the Aug. 2 default deadline, White House spokesman Jay Carney said Obama would be prepared sign an interim measure.

That plan is being worked out by Senate Republican leader Mitch McConnell and Democratic leader Harry Reid. It calls for raising the debt ceiling by $2.5 trillion -- thereby avoiding default -- through the end of 2012. The plan also would dictate modest reductions in the deficit but not include tax increases.

Carney said a grand bargain that includes massive spending cuts as well as increased tax revenue would have to already be agreed to in principle before Obama would sign on to the interim measure.

The press secretary later announced through Twitter that Obama would meet later and separately with House Speaker John Boehner and Republican House leader Eric Cantor.

Democratic leaders in Congress were invited to the White House for talks with Obama Wednesday afternoon, a day after conservative tea party-backed Republicans in the House of Representatives passed largely symbolic legislation that would slash the U.S. debt and make additional borrowing contingent on passage of a constitutional balanced budget amendment.

That legislation faced almost certain defeat in the Democrat-controlled Senate, and Obama has vowed to veto it should it ever reach his desk.

Before the House could vote or even fully debate its bill, Obama moved to undercut it when he marched into the White House press room to laud an unexpectedly rejuvenated bipartisan Senate plan -- that cuts spending and raises taxes -- as "broadly consistent" with his ideas for cutting the nation's debt. He held out hope it would provide an opening for both houses of Congress to raise the debt ceiling.

The plan by the Senate's so-called bipartisan Gang of Six is far too complicated and contentious to advance before an Aug. 2 deadline to avoid a default that Treasury Secretary Timothy Geithner and other experts warn would rattle markets, drive up interest rates and threaten to take the country back into a recession. But its authors clearly hope that it could serve as a template for a "grand bargain" later in the year that could erase perhaps $4 trillion from the debt over the coming decade.

Unless Congress agrees to increase the federal borrowing limit beyond the current cap of $14.3 trillion, the administration will be unable to pay all the government's bills. That would leave the Obama administration with the hard choices of whether to make payments to holders of Treasury bonds or send out checks to retirees relying on Social Security, the government-run pension plan.

Speaking on the Senate floor Wednesday, Democratic leader Harry Reid said he was confident Obama and congressional negotiators could avoid a government default, but the Senate still needed to hear from the House.

"We have a plan to go forward over here so I await word from the Speaker," said Reid, who also mentioned that he spoke to Obama Tuesday night.

The alternative Senate plan languished for months but returned to the fore when Republican Sen. Tom Coburn rejoined the group this week. It would seek an immediate $500 billion "down payment" on cutting the deficit as the starting point toward slashing indebtedness by slightly less than $4 trillion over the coming decade. That action would be finalized in a second piece of legislation.

The Gang of Six -- three senators from each party -- briefed other senators on the group's plan after a seemingly quixotic quest that took months, drew disdain at times from the leaders of both parties and appeared near failure more than once.

The plan as described Tuesday was almost certain to upset the core constituencies of both parties.

Liberal Democrats oppose efforts to make major cuts in cherished social programs. The Senate plan includes steps to slow the growth of Social Security, the federal pension plan for retirees, and to cut at least $500 billion from Medicare and Medicaid, the federal programs that subsidize health care for the elderly and poor.

The plan would also raise revenues by about $1 trillion over 10 years through a major overhaul of the tax code, challenging Republican Party orthodoxy that has held sway for two decades.

There was no assurance such a plan would win support in the House, where nearly all Republicans remain steadfast in their opposition to including any tax increases in a deficit-reduction plan. But in the Senate at least three more Republicans signed on as supporters of the Gang of Six.

"We have an opportunity to act like statesmen and avoid a debacle on Aug. 2, and it seems to me that all of our efforts should be focused on that," said Republican Sen. Roger Wicker. He and others said the plan was well-received at a weekly closed-door meeting of Republican senators.

Democrats said the House measure that passed Tuesday night, with its combination of cuts and spending limits, would inflict damage on millions who rely on the government's social safety net. "The Republicans are trying to repeal the second half of the 20th century," said Democratic Rep. Sander Levin.

Still, the House vote -- by allowing the Republicans to demonstrate their ideological purity -- might give lawmakers from conservative districts the political cover they need to move toward support of the bipartisan Senate plan as a means of raising the debt ceiling to avert an unprecedented U.S. default.

Obama stopped short of endorsing the Gang of Six plan, saying administration officials were analyzing it and not all details were known.

But he said it included "a revenue component" along with savings in Medicare and Social Security, making it the sort of balanced approach he has long advocated. He called the plan "a very significant step" that "is broadly consistent with what I've proposed."