WASHINGTON—A political meltdown followed quickly after the financial meltdown.

Facing the possible collapse of major Wall Street institutions, President Bush had proposed an extraordinary package, to be fueled by $700 billion in taxpayers’ money. It seemed to have the support — in body language if not words — of heavy hitters in both parties.

Rarely, it seemed, had Washington responded so quickly with something so large, to a problem so dire. And it was, like the credit bubble itself, an illusion.

The package fell apart in a multitude of ways — the phone calls from angry constituents, the feeling by House Republicans that they were being snubbed, the sudden and unwelcome injection of the presidential campaign. Talks were revived Friday and a Democratic negotiator, Rep. Barney Frank, dared to predict an agreement “that people can understand” by the end of the weekend.

All the frustrations poured out at a White House meeting that officials had hoped would be a celebration, of sorts, of a quick deal. As the nation’s most powerful officials sat around the White House Cabinet Room’s table Thursday, it fell to one of the lowest-ranking to force the key question.

Frank, a gruff and rumpled Democrat from Massachusetts, demanded to know which of two competing financial rescue plans Republican presidential nominee John McCain supported.

With Bush, Congress’s top leaders and McCain’s Democratic opponent, Barack Obama, watching intently, McCain declined to say, according to one person who was present and others briefed by attendees.

The exchange touched off chaotic rounds of questions and barbs that Bush at times struggled to control. McCain’s campaign later called it “a contentious shouting match.”

Bush himself appealed to the group at one point, “Can’t we just all go out and say things are OK?” according to two participants. That request for a publicly united front was rejected.

What McCain, Bush and other Republicans had hoped would be a moment of triumph — bipartisan in name, but more helpful to McCain than to Obama — turned into a political meltdown. Treasury Secretary Henry Paulson begged Democratic participants not to go before the cameras and reporters waiting outside the West Wing, even dropping to one knee half-jokingly.

Republicans, including Senate Minority Leader Mitch McConnell and House Minority Leader John Boehner, also slipped away without talking to reporters, unaware that one colleague — Sen. Richard Shelby, R-Ala. — went to the microphones alone to denounce the $700 billion bailout package Bush was desperately trying to enact.

“I’m probably not welcome again,” Shelby said, a candid remark in a day full of confusion, obfuscation and misunderstandings.

Presidents and presidential nominees have quarreled with their party’s congressional members before. But rarely have the clashes been so public nor the stakes so high as Thursday’s matinee drama at the White House.

Bush and Paulson seemed almost within grasp of an agreement for some version of the bailout plan, which they said was crucial to avoiding severe economic consequences. Their plan would spend billions of tax dollars to buy toxic mortgage security packages, a bid to keep credit available. Presumably, some of the money would be recouped when the packages were eventually resold at lower prices.

Senate approval was all but assured. House Democrats, too, signaled they probably would go along, while grudgingly, aware that millions of voters hated the notion of a tax-paid Wall Street bailout.

The trouble spot was House Republicans. For days, many had complained about the Bush plan’s costs and uncertainty. But not until Thursday did Democrats and even the administration realize how many of them had coalesced behind an alternative plan calling for the government to insure troubled loan packages rather than buy them.

The pivotal player was Boehner, a tall, deeply tanned and generally well-liked Ohioan. Boehner had been giving mixed signals for days, sometimes seeming inclined toward the Bush proposal, sometimes emphasizing his colleagues’ misgivings.

In a meeting Wednesday with Paulson and House Speaker Nancy Pelosi, D-Calif., Boehner cited his colleagues’ objections to the Bush proposal. But he did not propose an alternative, and his joint statement with Pelosi raised no alarms for the White House.