"The president believes it is important for the American people to fully understand the depths of the crisis affecting our country, how that affects them," White House press secretary Dana Perino said in announcing the speech. "I think everyone will tune in tonight because we are facing a once-in-a-century crisis in our financial markets."

The address, to be delivered from the White House's grand East Room, is to be between 12 and 14 minutes long, Perino said. Bush last gave a prime-time address to the nation 377 days ago, on the Iraq war, when he announced a gradual reduction in U.S. forces there. This one, expected to be carried by all five major television outlets, could be the last of his presidency.

The meltdown among several financial institutions and intense negotiations with Congress over the administration's requested $700 billion bailout package led the president to return to Washington early Wednesday from a three-day stay in New York. He canceled a planned trip to Florida, where he had been scheduled to raise campaign cash for Republican candidates.

The package is meeting with deep skepticism in Congress, especially from conservatives in Bush's own party who are revolting at the high price tag and unprecedented government intervention into private markets.

In the face of this, White House and administration officials have warned repeatedly of disaster if the debate is delayed, with Perino saying Wednesday that the nation risks "financial calamity" without bold action.

But that argument has not closed the deal, so Bush's goal clearly was to try to get to lawmakers by framing the debate in layman's terms that persuades the public to demand action from their representatives in Washington.

"The cold on Wall Street could infect Main Street," Perino said. "(People) are concerned about their homes, their education funds, their retirement accounts, their savings. ... I think Americans are plenty smart on this, but more information is certainly better."

Bush does not plan to dwell on how the problem developed, but on thanking lawmakers for working quickly, Perino said.

Throughout the crisis, the White House has struggled to determine how best to deploy Bush.

As the problem mushroomed over the weekend of Sept. 13, Bush generally stayed out of the limelight, letting Treasury Secretary Henry Paulson and Fed Chairman Ben Bernanke take the lead with reporters, lawmakers and the public. He even canceled a planned statement on the economy last Tuesday and remained silent for days.

Since Thursday, the president has said something publicly on the situation almost every day _ albeit very briefly most times _ and yet he still has had trouble breaking into the debate. News coverage has barely mentioned Bush's comments. Points that he and his White House aides have tried to make about the aim and substance of the bailout plan have been covered mostly on the periphery of the story.

The decision to pull out perhaps a president's largest available weapon _ the ability to command attention on evening television screens throughout the U.S. from a setting with the ultimate bully-pulpit power _ is one sign that the package faces still-daunting hurdles.

Networks generally grant a president time for major addresses when the White House asked for it. But TV executives cannot be thrilled about the timing _ this is the much-promoted week when the networks unveil their first episodes of the new season for high-profile shows.

Earlier in New York, Bush said he believes a plan will be passed despite the furious back-and-forth.

"I am confident when it's all said and done, that there will be a robust plan," the president said while at one of the last events on his trip to attend the annual U.N. General Assembly.