The Republican leader, Representative John A. Boehner of Ohio, had urged his colleagues to vote yes. “We know if we do nothing this crisis is likely to worsen and put us in an economic slump the likes of which we have never seen,” he said. “I am going to vote for this bill because I think it’s in the best interests of the American people.”

Opponents of the bailout called it a costly Band-Aid that did not address the core problems in the financial system. “Some things have changed in this bill but taxpayers will still be picking up the tab for Wall Street’s party,” said Representative Marilyn Musgrave, Republican of Colorado. “I am voting against this today because it’s not the best bill. It’s the quickest bill. Taxpayers for generations will pay for our haste and there is no guarantee that they will ever see the benefits.”

Among House Democrats as well as Republicans, many lawmakers facing the toughest challenges for re-election remained in the no column. Those with easier races were more likely to switch.

Many said they agonized over the decision amid a torrent of calls from constituents. Several who switched to yes cited a provision added by the Senate increasing the amount of savings insured by the Federal government to $250,000 per account, from $100,000.

Fears about the economy also motivated support. “Nobody in East Tennessee hates the fact more than me that I am going to vote yes today after voting no on Monday,” Representative Zach Wamp, a Republican, said.

“Monday I cast a blue-collar vote for the American people,” he continued. “Today I am going to cast a red, white and blue-collar vote with my hand over my heart for this country, because things are really bad and we don’t have any choice.”

Several Democrats in the Congressional Black Caucus said they were persuaded to support the bill by Mr. Obama.