WASHINGTON — Faced with unfavorable odds in the presidential campaign, John McCain time and again finds a way to roll the dice.

On Wednesday, with polls showing the financial crisis eroding his standing, the Republican nominee did it again -- tearing up his campaign schedule and announcing he would return here to participate in congressional deliberations over a rescue plan.

He also called on his Democratic rival, Barack Obama, to postpone their Friday night debate and join his decision to pull down ads and halt fundraising until a deal is done -- an invitation Obama summarily rejected.

By evening, both candidates had decided to head back to Washington today to meet at the White House with President Bush and congressional leaders. It was the culmination of a dizzying day of political one-upmanship that began when Obama placed an early-morning call to McCain in hopes of forging a joint statement of shared principles.

McCain's decision to up the ante was an audacious gambit to show leadership in a time of crisis. It drew the same kind of attention McCain received when he picked Alaska Gov. Sarah Palin as his running mate and, earlier, when he retooled himself as an ally of oil drilling as gas prices soared.

Much like the Palin selection, Wednesday's decision was made hastily, with aides scrambling to cancel McCain's meetings and appearance on David Letterman's show.

And, like naming a running mate untested on the national stage, it carries risks: Will voters view McCain's move as decisive, or unsteady, or even as an overtly partisan act to gain traction on an issue that he said Wednesday should transcend partisanship?

"He hopes to assume center stage in the economic discussion for the next two days," said Vin Weber, a Republican strategist and former congressman. "If he pulls it off, he'll get credit both for improving the plan to the benefit of taxpayers, and for assuring its passage and saving the economy."

Weber called it a "high-risk but potentially brilliant move."

McCain's moves came after two weeks in which he had struggled to gain his footing on the Wall Street meltdown. Democrats attacked him last week when he said the fundamentals of the economy were strong, while McCain, long an advocate of less government interference, tried to show support for stricter regulation.

As Washington confronted a crisis with its roots in the mismanagement of risk, it was unclear whether McCain's maneuvering would pay off.