Senate Majority Leader Harry Reid (D-Nev.) delayed a vote on his plan to raise the debt ceiling late Saturday to give President Obama and GOP leaders more time to strike an agreement. 

But the delay could imperil the chances of passing legislation to raise the debt limit by Aug. 2, a deadline set by Treasury Secretary Timothy Geithner for avoiding a federal default.

{mosads}A senior Senate GOP aide estimated Friday that leaders would have to reach a deal by 1 a.m. Sunday morning in order to push it through the upper chamber and get it to the House by Tuesday.

Leaders will have to rely on the goodwill of every member of the upper chamber to agree to unanimous consent to speed legislation through the Senate in time to make the deadline.

The senior GOP aide said members of the Tea Party Caucus who have been resistant to raising the debt ceiling would not drag out the floor procedure to delay a deal sanctioned by Democratic and Republican leaders.

A congressional source said Saturday night that Obama and GOP leaders had reached a tentative deal that would raise the debt limit by between $2.4 trillion and $2.8 trillion.

It would include spending cuts of about $1 trillion and set up a select bicameral committee to recommend a second deficit-reduction package worth between $1.4 trillion and $1.8 trillion by Thanksgiving.

If Congress fails to approve the committee’s recommendations, cuts to Defense and Medicare would go into effect automatically, giving both parties incentive to reach a later agreement.

The Medicare reforms would not include cuts to beneficiaries. Instead, the tentative deal would trim payments to healthcare providers and insurance companies, according to an aide familiar with the talks.

Senate Republicans would likely be given a vote on a balanced-budget amendment to the Constitution as part of the final deal.

Reid said White House officials asked him to postpone a vote on legislation he crafted to raise the debt ceiling by $2.4 trillion and cut spending by an equal amount.

Many details of the tentative bipartisan deal remain unresolved, according to Reid.

“There are many elements to be finalized and there is still a distance to go before any arrangement can be completed,” Reid said.

“I believe we should give everyone as much room as possible to do their work,” he said. “I spoke to the White House quite a few times this evening, and they’ve asked me to give everyone as much time as possible to reach an agreement, if one can be reached.”

Reid postponed a vote to end a GOP filibuster of his plan until 1:00 pm Sunday. The Senate adjourned at 10:13 p.m. Saturday and will reconvene at noon Sunday.

Senate Republicans had accused Reid of forcing a vote early Sunday morning in a deliberate attempt to run out the clock on bipartisan leadership negotiations. They saw it as a part of an effort to pressure moderate Republicans to go along with his own plan to raise the debt limit.

“Democrats are running out the clock. They want to delay the hard work of negotiation until the Aug. 2 deadline they’ve been warning us about all summer,” said Senate Republican Leader Mitch McConnell (Ky.).

Reid took to the floor Saturday afternoon to announce that Obama was not close to reaching a deal with House GOP leaders.

“The Speaker and the [Senate] Republican leader held a press conference to announce they’re in talks with the president and that a bargain to raise the debt limit is in the works and is close,” Reid said. “Members of the Senate, that is not true.”

Reid reported that he had spent two hours with Obama and Vice President Biden and asserted that Republicans “still refuse to negotiate in good faith” because they refuse to allow potential tax increases.

McConnell and House Speaker John Boehner (R-Ohio) offered a bullish assessment earlier in the day, surprising some senior Democrats who did not realize there was any substantial progress.

Democrats took to the Senate floor Saturday night to urge Obama to use unilateral executive authority to increase the debt limit.

As the deadline approaches, they have become increasingly anxious over the partisan deadlock on an agreement.

“If we fail this, I hope the president will invoke the 14th Amendment and everyone should read it. It says the debt of the United States shall not be questioned. And if we can’t get together, the president will have to take that responsibility,” Sen. Barbara Boxer (D-Calif.) said.

But McConnell seemed confident Saturday that he and Boehner would be able to reach agreement with Obama.

{mosads}“Our country is not going to default for the first time in our history — that is not going to happen — we now have a level of seriousness and the right people at the table that we needed and thought we had, as the Speaker indicated last week,” McConnell said at a Saturday press conference.

McConnell’s announcement sparked alarm among some rank-and-file Democrats who were surprised by media reports nine days ago that Obama and Boehner were close to a deal that would have cut entitlements.

White House budget director Jack Lew insisted to Democrats at a private meeting on July 21 that there was no deal, but the next day senior administration officials told reporters that they were in fact very close to hatching an agreement.

One liberal Democratic senator said he hoped that House Democrats would act as a backstop and derail an agreement which would cut Medicare substantially without offering the possibility of raising taxes.

If Obama and GOP leaders cannot finalize an agreement, Reid will move ahead with his own plan, which would not touch entitlement programs. He has reached out to moderate Republicans in hope of persuading at least seven of them to support his plan.

So far, Sen. Scott Brown (R), who is facing reelection next year in Massachusetts, has signaled he would vote for Reid’s proposal.

Forty-three Senate Republicans signed a letter to Reid on Saturday declaring their opposition to his debt-ceiling legislation. That opposition left Democrats short of the 60 votes needed to end a filibuster, virtually assuring the defeat of Reid’s plan when it came up for a scheduled vote.

Earlier Saturday, House Republicans resoundingly rejected a version of Reid’s debt plan in a 173-246 vote. Every Republican in the chamber voted against it, while all but 11 Democrats voted in favor.

However, Reid says there are more GOP lawmakers in play in the Senate than indicated by McConnell’s letter.

“One of the people who signed that letter has met with one of my Democratic senators,” Reid said. “A number of them have already agreed to work with us.”

Last Updated at 12:16 a.m.