President Barack Obama on Friday warned the United States was "almost out of time" to agree a deal to raise the nation's debt ceiling, insisting that a compromise was within reach.

"This is not a situation where the two parties are miles apart," Obama said in a White House statement, calling for a bipartisan deal and urging Americans to keep up the pressure on Republicans and Democrats to compromise.

"What's clear now is that any solution to avoid default must be bipartisan. It must have the support of both parties that were sent here to represent the American people. Not just one faction," Obama said.

Bitterly-divided lawmakers are seeking to hammer out a deal to raise the nation's $14.3 trillion debt ceiling before Tuesday when the Treasury says it will run out of the ability to borrow more funds to pay its bills.

The two sides have been wrangling for months over the details of such a deal, which is set to include deep spending cuts.

Obama was speaking after a conservative revolt left the Republican party in disarray scrambling to save a bill proposed by House Speaker John Boehner, even though Senate Democrats and the White House have insisted it will never pass.

"The debt ceiling does not determine how much more money we can spend, it simply authorizes us to pay the bills we already have racked up. It gives the United States of America the ability to keep its word," Obama said.

He said both sides roughly agreed how much spending should be cut, and on the steps to take in the coming months on tax reforms and putting in place some kind of enforcement mechanism.

"So there are plenty of ways out of this mess. But we are almost out of time. We need to reach a compromise by Tuesday so that our country will have the ability to pay its bills on time as we always have."

Obama said he was asking the American people to keep up their pressure on lawmakers to find a compromise, after a similar appeal on Monday crashed congressional websites and flooded the phone lines.

"For my part, our administration will be continuing to work with Democrats and Republicans all weekend long until we find a solution. The time for putting party first is over," the president said.

"The time for compromise on behalf of the American people is now. And I'm confident that we can solve this problem and I'm confident that we will solve this problem."