Hard-line conservatives on Friday tanked Speaker Kevin McCarthy’s long-shot bid to pass legislation to avert a government shutdown, in an extraordinary display of defiance that made it clear that Congress would almost certainly miss a midnight deadline on Saturday to keep federal funding flowing.

It appeared evident even before the vote that the stopgap bill was bound to fail, as several hard-right Republicans had declared that they would not back a temporary spending bill, known as a continuing resolution, under any circumstances. And the measure — which would slash spending and impose severe immigration restrictions — never had a chance of preventing a shutdown, since it was regarded as a nonstarter in the Democratic-controlled Senate.

But Mr. McCarthy, bracing for political blowback for a government closure, had scheduled it anyway in hopes of showing he was trying to avoid the crisis. And the decision by right-wing lawmakers to effectively blow up his one final effort to seize some political leverage in the shutdown fight dealt the speaker a stinging defeat while leaving politically vulnerable Republicans fuming.

The size of the group of defectors was striking, reflecting both Mr. McCarthy’s weak hold on his conference and the influence of the far right in the House. The bill failed by a vote of 232-198, with 21 Republicans joining all Democrats to oppose it.

From the moment the vote opened, the defections immediately began piling up and continued apace, exceeding even pessimistic predictions as more mainstream Republicans, particularly those from politically competitive districts won by President Biden, glumly watched the tally.

“Every time we vote for a continuing resolution, we make no changes in policy or spending,” said Representative Matt Gaetz, Republican of Florida, who led the charge against Mr. McCarthy’s funding plan. “It’s a vote to continue the status quo.”

President Biden condemned the blowup, as the White House dispatched his top budget official to brief reporters about the economic and national security risks of a shutdown.

“If the House fails to fulfill its most basic function, it fails to fund the government by tomorrow, it will have failed all our troops,” Mr. Biden said, speaking at Fort Myer in Arlington, Va., where he was attending Gen. Charles Q. Brown’s ascent to chairman of the Joint Chiefs of Staff. “Our service members will keep upholding their oath, showing up for work, standing sentinel around the world, keeping our country secure, but they won’t get paid. It’s a disgrace.”

The defeat in the House sent Republicans back to the drawing board with little more than 24 hours remaining before the shutdown deadline. Mr. McCarthy, a California Republican, told reporters he had “other ideas” on how to keep government funding flowing and that he would keep working to “make sure we solve this problem.” House leaders alerted lawmakers that more votes were expected on Saturday.

But the loss also made clear that Mr. McCarthy faces almost impossible odds of getting a stopgap funding bill through with votes from his own party alone, and that the simplest way to avert a shutdown would be for him to work with Democrats on a compromise measure. His detractors have warned that would prompt a move to oust him from the speakership.

House G.O.P. leaders emerged from a more than two-hour closed-door meeting held after the vote without a clear path forward to avert a shutdown. Much of the discussion centered around adjusting the same strategy that delivered Mr. McCarthy his defeat earlier in the day: trying to entice conservatives to vote for stopgap funding legislation by promising that it would give lawmakers more time to pass individual spending bills — their stated goal.

With a shutdown just a day away, House Republicans retired for the evening without a clear idea of what, if anything, they would be asked to support on the floor on Saturday. A bare-bones 14-day stopgap bill emerged as one possibility for Republicans, though it was far from clear if it could pass.

Republicans came out of the meeting “all over the map,” said Representative Steve Womack, Republican of Arkansas and a senior member of the Appropriations Committee. He predicted that House Republicans would soon be forced to consider the bipartisan stopgap plan moving forward in the Senate if they could not pass a funding bridge of their own.

The measure put to a vote on Friday would keep the government open for 30 days and during that period impose drastic cuts — in many cases as much as 29 percent — to government programs, except for funding for veterans, homeland security and disaster response. It did not include any military or humanitarian aid for Ukraine, and it directed the homeland security secretary to resume “all activities related to the construction of the border wall” at the southern border that were in place under former President Donald J. Trump.

Democrats said the cuts to social programs included in the stopgap were so severe that they would amount to a “government shutdown in and of itself,” said Representative Jim McGovern of Massachusetts, the senior Democrat on the Rules Committee. “It guts the heart and soul of our safety net.”

Mr. McCarthy’s allies defended the strategy of putting the doomed bill to a vote as a way to show the public that he tried to keep the government open but was foiled by a handful of his far-right members.

But the move also forced some of his most politically endangered members to go on the record supporting sharp cuts to popular social programs, and almost immediately after the vote on Friday, House Democrats’ campaign arm criticized them for supporting “a hyperpartisan continuing resolution that does absolutely nothing to avert a government shutdown.”

Representative Mike Lawler of New York, who is facing one of the toughest re-election races in the country, vented frustration at the 21 hard-liners who tanked the bill.

“The bottom line is there’s going to be a C.R. that gets passed,” Mr. Lawler said, using the shorthand for the continuing resolution. “And these folks, frankly, for the things that they advocate for and want — they’re going to be worse off as a result because they didn’t want to work as a conference.”

Following the failed vote, Representative Hakeem Jeffries of New York, the Democratic leader, blamed the funding impasse on an ongoing Republican “civil war” and Mr. McCarthy’s decision to abandon a spending deal struck with President Biden earlier this year. He said the only way forward is for Mr. McCarthy to put on the floor a bipartisan stopgap bill under consideration in the Senate, with a key vote scheduled for Saturday.

“It’s not that complicated,” Mr. Jeffries said.

The defeat also left the House in an exceedingly weak position to negotiate with the Senate, which is moving ahead with its own, bipartisan short-term funding plan that could see a vote as soon as this weekend. That bill would continue spending at current levels for six weeks and provide $6 billion in aid to Ukraine and $6 billion for natural disaster relief at home.

“The speaker has spent weeks catering to the hard right, and now he finds himself in the exact same position he’s been in since the beginning,” Senator Chuck Schumer of New York, the majority leader, said. “No plan forward, no closer to passing something that avoids a shutdown. The speaker needs to abandon his doomed mission of trying to please MAGA extremists and instead he needs to work across the aisle to keep the government open.”

John Ismay contributed reporting from Arlington, Va.