Mr. Obama, in the ABC News interview, suggested that banks would be required to reveal more about their mortgage holdings.

Image BANKING RESCUE, REDUX Treasury Secretary Timothy F. Geithners speech and testimony drew a lukewarm response. Credit... Joshua Roberts/Bloomberg News

“Essentially what you’ve got are a set of banks that have not been as transparent as we need to be in terms of what their books look like. And we’re going to have to hold out the Band-Aid a little bit and go ahead and just be clear about some of the losses that have been made because until we do that, we’re not going to be able to attract private capital into the marketplace.”

The day was the first big test of Mr. Geithner as Treasury secretary, who has one of the toughest sells in America: convincing lawmakers and taxpayers that they should again bail out the very banks whose mistakes contributed to the loss of more than three million jobs and caused acute financial pain.

It was clear during the hours he spent before the cameras and lawmakers that he was well-spoken and thoughtful. But his career until now had played out behind the scenes as a civil servant and a central banker. He occasionally lapsed into financial jargon and struggled to connect to a broader public audience.

As the day wore on, Mr. Geithner faced growing skepticism from Democratic and Republican lawmakers, many of them channeling deep voter disgust with the way the government has handled the bailout over the last nine months.

Even Democrats who are supportive of the administration said that it had failed to provide more information about how it would be spending the remaining money in the bailout program.

“We need more details from Treasury on how exactly it plans to remove bad assets while protecting the taxpayer,” said Senator John Kerry, the Massachusetts Democrat who is a senior member of the Senate Finance Committee. “We have zombie banks that are weighed down because their liabilities exceed their assets. Without a precise mechanism for addressing toxic assets, it will be difficult to increase lending.”