Sen. John McCain's unilateral decision to suspend his campaign has jeopardized tomorrow's highly anticipated presidential debate and could influence, for good or for ill, the precarious negotiations over a Wall Street bailout package.

Speaking shortly after the Republican's surprise announcement, Sen. Barack Obama rejected his opponent's call to postpone the debate. While emphasizing his willingness to work with Mr. McCain in the financial talks, he said the crisis made it even more important for the candidates to be able to discuss their views.

Mr. McCain said the two sides should suspend partisanship until a bailout package is finalized. Mr. Obama countered with the observation that the president should be able to do more than one thing at once.

One of many questions left by the dueling announcements was which candidate would blink first on the timing of the debate, still scheduled to be held tomorrow night at the University of Mississippi in Oxford.

The impasse came as both sides tried to project an air of leadership in the credit market talks. In recent days, the rivals have expressed generally overlapping concerns about the package under negotiation on Capitol Hill, but neither has played any material role in the negotiations.

Mr. McCain was pessimistic about the Capitol Hill efforts.

"It has become clear that no consensus has developed to support the administration's proposal. I do not believe that the plan on the table will pass as it currently stands, and we are running out of time," Mr. McCain said in a mid-afternoon appearance in New York City announcing the decision to suspend his campaign.

The Republican took no questions after his brief statement.

In a news conference a little while later, Mr. Obama said normal campaigning, including the debate, should continue. He suggested that the course his opponent advocated could politicize rather than de-politicize talks on the rescue package.

"It's my belief that this is exactly the time the American people need to hear from the person who, in approximately 40 days, will be responsible with dealing with this mess," the Illinois Democrat said from his debate preparation site in Florida. "What I think is important is that we don't suddenly infuse Capitol Hill with presidential politics."

Arguing that the fiscal crisis should not push the campaign aside, he said, "Presidents are going to have to deal with more than one thing at a time. It's not necessary for us to think that we can do only one thing, and suspend everything else."

Mr. Obama said he was willing "to be anywhere at any time" if that would assist the talks.

"We've both got big airplanes," he said of himself and his rival.

The unexpected turn in a constantly surprising campaign came after a day of behind-the-scenes communication and miscommunication between the two candidates. Shortly after Mr. McCain spoke from his Manhattan hotel, Mr. Obama's press secretary, Bill Burton, issued a statement saying that at 8:30 that morning, Mr. Obama had suggested to his Republican rival that they issue a joint statement on the crisis.

Later in the day, Mr. McCain agreed to the plan, but did not mention it in his remarks shortly thereafter suspending his campaign.

Late last night, the three-paragraph joint statement was issued. "This is a time to rise above politics for the good of the country," it said. "We cannot risk an economic catastrophe. Now is our chance to come together to prove that Washington is once again capable of leading this country."

Aides said Mr. McCain had alerted the White House of his intent to stop campaigning. In his speech to the nation last night, President Bush said he had invited both candidates, along with congressional leaders, to a White House meeting today.

Reaction to Mr. McCain's announcement broke along predictable partisan lines.

"It's the longest Hail Mary pass in the history of either football or Marys," said Rep. Barney Frank, D-Mass., one of the key House negotiators on the fiscal package.

In an interview with the Web site Politico, Republican commentator Kevin Madden said, "This is the McCain that swing voters love."

"The American electorate has a greater appetite for action, however unconventional it is, than it does for political debates and the way they are currently constructed," said Mr. Madden, who was presidential campaign press secretary for former Massachusetts Gov. Mitt Romney.

In recent days, several national and state polls have shifted in Mr. Obama's direction. And with varying margins, the consensus of those surveys has shown voters placing greater faith in the Democrat's ability to manage the economy than in Mr. McCain's ability. The McCain camp took unusual pains yesterday to contest the results of an ABC/Washington Post survey, released Tuesday, that showed a sharp jump in support for Mr. Obama.

The survey placed Mr. Obama's margin at 52 percent to 43 percent, a dramatic shift in his favor. Rebutting those findings, Bill McInturff, the McCain campaign's pollster, argued that the survey's sample had included a disproportionate number of Democrats. In response, ABC's polling department issued a memo noting that the survey's partisan breakdown was essentially the same as its earlier polls throughout the year.

Other national polls tended to show more modest leads for Mr. Obama, contrasting with a trend in Mr. McCain's direction in the days immediately after the GOP convention in Minnesota.

Rasmussen Reports put the race at 49 percent to 47 percent in its daily tracking poll. The Gallup organization saw a 47-44 percent race, while a Fox News survey found a 45 percent-to-39 percent lead for the Democrat.

A variety of state surveys found a similar, though modest, trend away from Mr. McCain. Among them was a new CNN/Time survey that showed a surprisingly comfortable edge, 53 percent to 44 percent, for Mr. Obama in Pennsylvania.