Washington - Republican John McCain and Democrat Barack Obama are scheduled hold their first presidential debate late Friday, but now the two campaigns can't agree on whether they should proceed or stay in Washington to address the nation's financial crisis.

McCain kicked off the uncertainty Wednesday when he announced he was suspending his campaign to return to Washington to work on emergency legislation that the White House wants from Congress to rescue financial markets.

McCain said that the planned debate at the University of Mississippi should be postponed so the two senators could work on the 700-billion-dollar bailout package and attend a White House meeting with President George W Bush.

Obama agreed to join the meeting, flying to Washington and joining McCain to sit down with the president, his economic team and top leaders in Congress. But Obama insists the debate must go on with the November 4 elections looming.

"It's my belief that this is exactly the time when the American people need to hear from the person who in approximately 40 days will be responsible for dealing with this mess," Obama said.

But McCain has not said whether he will attend the debate in the town of Oxford, Mississippi, even as the university has continued to prepare the stage for the first showdown between the 72-year-old McCain and the 47-year-old Obama.

McCain's ambiguity has left the university, media and public wondering when they'll get the chance to see the candidates square off in what was billed as a foreign policy debate but will now surely include a questions about the economic crisis and Bush's bailout proposal - the largest in US history.

Obama said he would like to see his opponent join him on stage.

"I hope he does," Obama told CNN late Thursday. "I'm not going to speculate at this point. ... I'll be monitoring the situation."

McCain's announcement on Wednesday that he was putting his campaign on hold appeared at first to be a cunning move to upstage Obama on the economic crisis and halt a trend among voters who believe Obama is more qualified to manage the economy, which has become the top issue in the presidential race.

"Now is our chance to come together to prove that Washington is once again capable of leading this country," McCain said.

But by Thursday, McCain found himself the target of Democrats who argued he was politicizing the economic crisis and that his presence in Washington had become a distraction from congressional efforts to hammer out legislation and reach a deal with the White House.

"This is what I need to do for my country, and if that hurts me politically, well, I'll gladly take the penalty," McCain told broadcaster NBC News.

"I'm very hopeful that we'll get enough of an agreement (Friday) that I'll make this debate," McCain added.

Bush administration officials have been in discussions with Congress about the emergency proposal since last week but face growing criticism from conservative Republicans who believe the proposal violates free-market principles. Majority Democrats argue it lacks adequate protections for taxpayers footing the bailout cost and homeowners with failing mortgages.

A Washington Post-ABC News national poll released Wednesday gave Obama a widening lead of 52 per cent to 43 per cent over McCain, with voters expressing more trust in Obama on the economy. (dpa)