WASHINGTON - House Speaker John A. Boehner spent much of Thursday confidently predicting that he could pass a plan to avoid the year-end fiscal cliff.

"Sure did," Boehner acknowledged with a wry smile Friday, the day after he was forced to cancel the vote due to lack of support. The stunning rebuke by his fellow Republicans was the most critical test of Boehner's leadership since he assumed control of the new Republican majority two years ago and called into question Boehner's ability to lead his GOP majority.

"I think the speaker's legacy and his leadership are at stake here," said Lee Hamilton, an Indiana Democrat, who served more than 30 years in the House and is director of the Center on Congress at Indiana University. "This is a major moment in his career."

Hamilton said that, ultimately, the Ohio Republican's reputation probably will be determined by whether Congress and President Obama manage to cut a fiscal-cliff agreement, not by one legislative setback. But late Thursday, Boehner failed to get the 217 votes he needed to pass a plan to extend tax breaks for more than 99 percent of Americans, while allowing them to rise for those making more than $1 million a year. He had already failed to reach a broader bipartisan deficit-reduction plan in one-on-one talks with Obama, but the collapse of his own plan left Boehner tossing up his hands and insisting that it was now up to the president and the Democratic-controlled Senate to solve the crisis.

Boehner vowed Saturday to "continue to work with our colleagues in the Congress and the White House on a plan that protects families and small businesses." But, in the GOP's weekly taped address, he reiterated Republican opposition to tax increases and called for more concessions from the White House.

Asked Friday if he is concerned that his title might be jeopardy, Boehner answered simply: "No. I'm not."

The episode provided a public demonstration of how difficult it will be for Republicans to vote for any tax increase, potentially impressing on Obama that he must offer more than the $930 billion in spending cuts included in his latest offer to Boehner if he hopes to convince Republicans that tax rates should rise for the wealthy.

And while Boehner could not muster the near-unanimous support he needed to pass his bill without Democratic support, Republican leaders spent two days securing commitments from members willing to back the plan - votes they could deliver to propel a bipartisan deal that also got votes from across the aisle.