The White House has warned that President Obama could veto a debt limit plan proposed by top House Republicans.
Meanwhile, Speaker John Boehner's plan to trim public spending and raise the limit met with resistance from rank-and-file members of his own party.
A House of Representatives vote on the plan was delayed from Wednesday after doubts arose over the cuts it proposed.
Washington remains deadlocked as a deadline to increase the government's borrowing authority looms on 2 August.
The US runs a budget deficit that topped $1.5tn (£920bn) this year, and has amassed a national debt of $14.3tn.
The government's authority to borrow more money has expired, and the US risks a default on its debt obligations if congressional and White House negotiators are unable to agree on a plan to increase the debt limit by 2 August.
The debt limit has been raised dozens of times in recent decades, mostly without partisan debate.
This year, though, conservative Republicans refused to allow an increase unaccompanied by dramatic cuts to the US budget deficit.
House of scorecards
The latest round of bargaining began on Monday when Mr Boehner and Senate Democrats offered competing plans to raise the debt limit and cut spending.
The plans differed in size and scope, and neither would raise new tax revenue - in recognition of Republicans' intransigence on that point.
Mr Boehner's plan would also require another debt limit agreement in about six months, something Mr Obama has publicly declared he will not accept.
On Tuesday, the White House budget office said in a statement that the Obama administration "strongly opposes" Mr Boehner's plan, adding that if it is presented to Mr Obama "the president's senior advisors would recommend that he veto this bill".
Mr Boehner was forced to rewrite his plan after the Congressional Budget Office, the official non-partisan score-keeper in fiscal legislation, said it would generate less than the $1.2tn (£730bn) in budget savings he had initially announced.
It was also slow to win support from rank-and-file Republicans in the House of Representatives, who have been pushing for steeper cuts.
Reports on Tuesday night said the legislation, scheduled for debate in the House on Wednesday, would now not make it to the floor until Thursday.
http://www.bbc.co.uk/news/world-us-canada-14303325
Note: Update Record,27 July 2011 Last updated at 02:12 GMT