"Any solution to avoid default must be bipartisan," Mr. Obama said. "I urge Democrats and Republicans in the Senate to find common ground on a plan that can get support from both parties in the House, a plan that I can sign by Tuesday."
Mr. Obama urged Republicans in the House and Senate to abandon a bill that "does not solve the problem" and has no chance of passage in the Senate."
"There are a lot of crises in the world that we can't always predict or avoid, he said. "This isn't one of those crises."
But there was no clear signal what the next step would be. Among the several possibilities were changes to the House bill, an attempt by Senate Democrats to leapfrog forward with their own plan, or a new attempt to reach a compromise on the part of all the major players.
In an effort to break the logjam, Senator Harry Reid, the majority leader, called on Senator Mitch McConnell, the Republican leader, to meet with him on Friday to try to resolve to the stalemate, given the failure of House Republicans to advance their own budget proposal.
"My door is open," Mr. Reid said as the Senate convened. "I will listen to any idea to get this done in a way that prevents a default and a dangerous downgrade to America's credit rating. Time is short, and too much is at stake, to waste even one more minute.
"The last train is leaving the station," he said. "This is our last chance to avert default."
Mr. McConnell, who had earlier been working with Mr. Reid on a fallback plan, abandoned that attempt and has been supporting the effort by the House speaker, John A. Boehner, to push through a proposal that would raise the debt limit in two stages - an approach flatly rejected by Senate Democrats and the White House. Mr. McConnell also had been talking with Vice President Joseph R. Biden Jr. but broke the conversation off while the Boehner plan was pending.
Mr. McConnell, too, came to the Senate floor and offered little indication that he was ready to deal, accusing Democrats of devoting recent days to undermining the House plan. "Our Democratic friends in the Senate have offered no solutions to the crisis that can pass either chamber," he said.
Mr. Reid said he would be moving within hours to force votes on his own plan to cut spending by about $2.5 trillion over 10 years and raise the debt limit through 2012, a move that would lead to a crucial showdown vote over the weekend. He said he would be making changes to his measure to attract more support but made clear that he considered the Senate plan the final effort to avert a default next week.
"There will be no time left to vote on another bill or consider another option here in the Senate," he said. "None."
Mr. Reid said he had also had a "sobering" conversation on Friday with Treasury Secretary Timothy F. Geithner about the consequences of a default.
"It is really precarious for our country," he said. Just minutes from a roll-call vote on the plan pushed by Mr. Boehner, Republicans stunned the House on Thursday by interrupting the debate and turning to routine matters while Mr. Boehner and his lieutenants tried to pressure reluctant conservatives into backing their plan. The House then went into a recess and shortly before 11 p.m., the leadership announced that no vote would be held.
The surprise postponement threw the endgame of the debt limit clash into confusion and raised concerns among some on Capitol Hill that the government was lurching toward a default. The White House and Senate Democratic leaders had been waiting for the House to act before making their next move with an eye on the Tuesday deadline set by the Treasury Department for raising the debt ceiling or facing the possibility that the government would not be able to meet all its financial obligations.
Republicans had expressed confidence throughout Thursday that they would round up enough recalcitrant conservatives to pass their plan, but they obviously miscalculated.
Officials and aides said opponents had multiple misgivings about the measure, which Senate Democrats had already said they would reject as soon as it reached the Senate desk. The legislation would provide a $900 billion increase in the federal debt limit in exchange for slightly more than that in spending cuts. A second increase of $1.6 trillion in 2012 would be tied to the ability of a new special committee to produce a proposal to save an additional $1.8 trillion.
Failure to pass the measure would represent a significant defeat for Mr. Boehner, the first-year speaker who has invested significant political capital in trying to get his fractious majority behind the legislation, which had the strong support of the entire leadership team. It could also bolster Senate Democrats in their push to raise the debt ceiling by enough to take the Treasury Department through 2012.
Though they knew the vote was going to be close given the philosophical objections of many House Republicans to an increase in federal borrowing power, Republicans had made it clear earlier Thursday that they expected to pass the legislation in an effort to force the Democratic-led Senate into accepting it.
"When the House takes action today, the United States Senate will have no more excuses for inaction," Mr. Boehner said Thursday afternoon, just before the debate began.
But shortly before 6 p.m., near the end of a two-hour debate on the plan, Republicans halted the proceedings, and Democrats claimed that Mr. Boehner was still short of the votes he needed.
At 6:50 p.m., the leaders stopped all business on the floor, where the House had worked through a list of post offices to be renamed, and called a recess. As the House remained dark, Republican leaders scurried from office to office, meeting with rebellious members and trying to find a way to press forward with the vote. They eventually surrendered and put off the vote for the night.
With House Democrats offering no votes, even from the party's fiscal conservatives, Republicans evidently remained shy of the total needed for passage, and Mr. Boehner engaged in some very public arm-twisting as he pulled members off the floor into a nearby office.
Republicans who met with the speaker, in his frantic search for votes, included Mo Brooks of Alabama, Jeff Flake and Trent Franks of Arizona, and two freshmen from Illinois, Randy Hultgren and Joe Walsh.
News of the prospect that the vote could be put off began circulating as Representative Nancy Pelosi, the Democratic leader and former House speaker, was making her party's closing argument against the plan on the floor. After the night of uncertainty, Ms. Pelosi said she hoped the struggle would make House Republicans more willing to give ground.
"Hopefully, now the Republicans will come back to the table to negotiate a bipartisan, balanced agreement that is overwhelmingly supported by the American people," said Ms. Pelosi, who added that "Republicans have taken us to the brink of economic chaos."
The delay caught Senate Democrats off guard. Mr. Reid had said earlier Thursday that once the House approved its plan, he intended to immediately set it aside and move ahead with his proposal for deeper spending cuts and a longer extension in the debt limit, which would ultimately be thrown back to the House.
The White House was taken by surprise by the postponement as well, having shared the expectation that Mr. Boehner had the Republican votes to pass his measure. Administration officials had no immediate reaction; any satisfaction at the public show of Republican disarray over a bill that Mr. Obama had threatened to veto was offset by concern that additional delays only raised the chances of missing the deadline to increase the debt limit.