Both sides have accused the other of political posturing
A debate between the US presidential rivals remains uncertain after the pair left talks in Washington without a deal on a bail-out for US financial markets.
Advisers to Republican John McCain said he had not decided whether to attend Friday's debate with Barack Obama.
Mr McCain suspended his campaign earlier this week, saying he needed to help to deal with the economic crisis.
Mr Obama said the head-to-head would show voters which candidate would better handle "this mess".
The US Commission on Presidential Debates said on Thursday that it was "moving forward" with its arrangements for the debate at the University of Mississippi at 2000 (0100 GMT).
But John McCain is still saying he will not be there unless there is a deal in Washington on the bail-out - which sums up how the financial crisis here has even overshadowed the presidential campaign, says the BBC's Kevin Connolly in Washington.
The two senators were among a number of congressional leaders who met President George W Bush on Thursday evening to discuss the massive $700bn (£380bn) government plan to bail out the finance sector.
Mr McCain was accused by angry Democrats of sabotaging the talks in order to try to promote his electoral fortunes.
HAVE YOUR SAY
McCain is wrong on this one. The debate should go on.
Scott, Seattle, USA
The head of the Senate Banking Committee, Christopher Dodd, described the meeting as a "photo opportunity and political theatre that had nothing to do with us getting to work".
Mr Obama also pointed a finger at his rival for the faltering outcome, saying: "When you start injecting presidential politics into delicate negotiations, then you can actually create more problems rather than less."
Mr McCain's camp accused the Democratic senator of playing politics and said there "never was a deal" and more work was needed to get both Republicans and Democrats on side.
Mr McCain said he was "hopeful" that a deal would be reached soon, with discussions set to resume later on Friday.
"There are a variety of concerns, I think a lot of them have been satisfied," Mr McCain said in a television interview.