A scheduled showdown vote Thursday evening in the U.S. House will determine how Congress and the White House proceed on fiscal cliff negotiations.
Hours before the vote, both sides insisted that they were open to further talks but also resorted to heated political rhetoric as time for a deal continued to disappear.
With less than two weeks until the automatic tax increases and spending cuts of the fiscal cliff take effect, the House will consider two Republican measures in the latest wrinkle in tense negotiations between Speaker John Boehner and President Barack Obama.
The GOP proposals are an alternative to a broader deal that both sides say they want but has been impossible to reach due to deep ideological divides over the size and role of government.
One of the measures would amount to both a concession by Republicans and a hard-line stance against the president on taxes. It would extend tax cuts scheduled to expire at the end of the year for most people while allowing rates to increase to 1990s levels on income over $1 million.
The second proposal would change the automatic spending cuts set to kick in next year under the fiscal cliff, replacing cuts to the military with reductions elsewhere.
Despite trouble corralling Republican votes for his plan, Boehner said Thursday that both measures would pass, putting the onus on Obama and Senate Democrats to either accept them or offer a compromise.
He blamed Obama for failing to deliver an acceptable proposal in their talks, which appeared to progress over the weekend and Monday before stalling again.
"For weeks, the White House said that if I moved on rates, that they would make substantial concessions on spending cuts and entitlement reforms," Boehner said of breaking from his past opposition to any kind of tax rate increase. "I did my part. They've done nothing."
He added that Obama seems "unwilling to stand up to his own party on the big issues that face our country."
However, the White House and Senate Democrats said it was Boehner who was buckling to demands by his party's conservative base, accusing him of following a past pattern of backing off as the negotiations started to approach a possible deal.
Senate Majority Leader Harry Reid, D-Nevada, immediately rejected any chance the Senate will take up the House measures, calling them "pointless political stunts."
He and other top Senate Democrats said Boehner must instead work out an agreement with Obama on a more comprehensive approach. Otherwise, they said, the House should approve a Senate-passed measure that adheres to Obama's longtime call for extending current lower rates on income up to $250,000 for families.
White House spokesman Jay Carney called the Republican alternatives "a major step backwards in these discussions and a major step backward for the American people."
He noted that the GOP proposals would result in extended tax cuts averaging $50,000 for millionaires and billionaires, which he said went against what Obama campaigned in winning re-election last month.
Despite the tough talk, Boehner, Carney and Senate Democratic leaders all said they were ready to continue negotiating, even as time was running out.
"I remain hopeful," Boehner said. "Our country has big challenges, and the president and I going to have to work together to solve those challenges."
His No. 2, Majority Leader Eric Cantor, R-Virginia, earlier said House members will remain in Washington after the votes later Thursday, indicating the possibility of further negotiations.
Reid noted that Senate work would be put off for a memorial service Friday in Washington and the funeral Sunday in Hawaii for Democratic Sen. Daniel Inouye, who died this week. The Senate would return to work on December 27, two days after Christmas, Reid added.
Senior administration officials said Obama and Boehner have not spoken to each other since Monday, when the president made a counter-proposal to a Republican offer over the weekend. Boehner then proposed his alternative approach Tuesday.
The White House threatened Wednesday to veto Boehner's tax plan, saying it would achieve little and diverted the focus from efforts to negotiate a broader agreement to reduce the nation's chronic federal deficits and debt.
While considered a negotiating tactic to pressure Obama to make more concessions, the House votes Thursday also seek to turn public opinion that now backs the president over Republicans in the talks.
A new CNN/ORC International poll Thursday showed that just over half of respondents believe Republicans should give up more than Democrats in any bipartisan solution to the country's problems.
The survey also indicated that a narrow majority of Americans consider the Republican Party's policies and views as too extreme, a first for the GOP, while fewer than a third said they trust congressional Republicans more than the president to deal with the major issues facing the nation.
Meanwhile, civil rights and child advocacy groups complained Thursday that the Republican alternatives to be voted on that night would end some tax benefits that help the poor and families with children. Carney said the GOP measures would mean higher taxes on 25 million families.
Until Boehner essentially halted negotiations by introducing his so-called Plan B on Tuesday, the two sides made progress on forging a $2 trillion deficit reduction deal that included new revenue sought by Obama and spending cuts and entitlement changes desired by Boehner.
The stakes are high, as economists say that failure to reach an agreement could spark another recession.
Boehner described his Plan B as a fallback option to prevent a sweeping tax hike when tax cuts from the administration of President George W. Bush expire at the end of the year. Sources said the Boehner measure also would include extending the current estate tax and alternative minimum tax, two steps sought by Republicans.
GOP leaders also had planned to vote Thursday on Obama's longstanding proposal to extend the Bush-era tax cuts on income up to $250,000, a lower threshold than Boehner's alternative.
However, Republicans decided to drop the vote on Obama's version, which was a major theme of the president's re-election campaign. In the negotiations, Obama had agreed to raise his threshold to income over $400,000, and a GOP aide said that change made a vote on the original plan unnecessary.
At the same time, Boehner was having trouble rounding up Republican support for his Plan B. With Democrats expected to oppose it, the speaker can afford only about two dozen GOP defections to get it passed.
Because of their difficulty in securing votes from conservatives, GOP leaders added a vote Thursday on the separate measure that would replace automatic spending cuts to defense with cuts elsewhere.
Obama said at a news conference Wednesday that Republicans were focused too much on besting him personally rather than thinking about what's best for the country.
"Take the deal," Obama urged Republicans, referring to the broader proposal. He added that it would "reduce the deficit more than any other deficit reduction package" and would represent an achievement.
"They should be proud of it," Obama said. "But they keep on finding ways to say 'no' as opposed to finding ways to say 'yes.' "
In his own statement Wednesday -- a 52-second appearance before reporters in which he took no questions -- Boehner said the president had yet to offer a balance between increased revenue and spending cuts that he has been promising.
While the Boehner plan represents a concession from his original vow to oppose any tax rate increase, it sets a higher threshold than the $400,000 sought by Obama.
Boehner said that once his plan passes the House, Obama can either persuade Senate Democrats to accept it or "be responsible for the largest tax increase in American history."
Anti-tax crusader Grover Norquist provided political cover for Republicans who have signed his pledge against tax increases, saying Wednesday that legislators who vote for Boehner's Plan B would adhere to the intent of their promise.
The Obama administration and congressional Democrats said Boehner changed course because he was unable to muster Republican support for the larger deal being negotiated with the president.
Sen. Patty Murray of Washington, the top Democrat on a special joint congressional panel set up last year that failed to reach a deficit reduction agreement, said the pattern of this negotiation repeated the past.
"It seemed like every time we were this close to deal, every time it looked like real and fair revenue would be on the table, every time we had a balanced and bipartisan deficit reduction plan within our grasp, Speaker Boehner would look over his shoulder, see Grover Norquist and the tea party and scurry right back to his partisan corner," Murray said Thursday.
Boehner, however, said Obama and Democrats remained unwilling to seriously address the spending cuts and entitlement reforms necessary.
He said that in initial discussions, Treasury Secretary Tim Geithner outlined a minimum possible deal that was close to the counter-proposals being negotiated this week.
"I said, 'Then why should we address the minimum plan?' " Boehner added.
At his news conference Wednesday, Obama alluded to Friday's Connecticut school shootings in calling on Republicans to put aside political brinksmanship.
"Right now, what the country needs is for us to compromise," Obama said, describing the GOP refusal to accept a compromise as "puzzling."
Asked why an agreement was proving so elusive after both sides had made concessions, Obama said it might be that "it is very hard for them to say 'yes' to me."
"At some point, they've got to take me out of it," Obama said of Republicans, adding that they should instead focus on "doing something good for the country."
Obama and Democrats argue that increased revenue, including higher tax rates on the wealthy, must be part of broader deficit reduction plan to prevent a tax increase on middle-class Americans.
Polls have consistently showed support for the Obama plan, and some Republicans have called for acceding to the president on the tax issue in order to focus on cuts to spending and entitlement programs.
Both the GOP's weekend proposal and Obama's response included concessions, raising hopes that a deal was within reach. Since then, conflict rather than compromise has been the public posturing of the talks.
Obama's latest counter-proposal on Monday generated protests from the liberal base of the Democratic Party because it included some changes to entitlement programs such as Social Security, Medicare and Medicaid.
In particular, liberals cited Obama's willingness to include a new formula for the consumer price index applied to benefits to protect against inflation.
The new calculation, called chained CPI, includes assumptions on consumer habits in response to rising prices, such as seeking cheaper alternatives, and would result in smaller benefit increases in future years.
Statistics supplied by opponents say the change would mean Social Security recipients would get $6,000 less in benefits over the first 15 years of chained CPI.
Carney said Obama's consumer price index proposal "would protect vulnerable communities, including the very elderly, when it comes to Social Security recipients." He called the president's acceptance of the chained CPI a signal of his willingness to compromise.
CNN's Joe Sterling and Ted Barrett contributed to this report.