SALT LAKE CITY — Senator Robert F. Bennett, an 18-year veteran Republican who had been seeking a fourth term this fall, was stripped of his party’s nomination on Saturday at the state convention, becoming one of the first Congressional victims of the surging ferment of discontent from the Tea Party-infused Republican right.

Steve C. Wilson/Associated Press

Mr. Bennett, 76, was outmatched in delegate votes by two relative newcomers despite an enthusiastic endorsement and convention speech from Mitt Romney, the former Massachusetts governor and local Utah hero, and a political pedigree of deep Mormon roots and public service.

“You know his principles,” Mr. Romney said to the roughly 3,500 delegates. “We need Bob Bennett’s skill and loyalty and intellect and power.”

Mr. Bennett himself, in his final appeal from the dais, said the stakes in Washington were simply too high to take a chance on the unknown.

“Keep the veteran on the floor when you’re playing a championship game,” he appealed to the delegates.

But the delegates were not in the mood, and the two leading challengers, Tim Bridgewater, 49, a businessman, and Mike Lee, 38, a lawyer, were also united in wanting Mr. Bennett out.

“Our anything-but-Bennett bond is strong,” said William Lee, the field director for the Lee campaign. Mr. Lee, who is no relation to Mike Lee, said some delegates for each side were pledged to switch to Mr. Lee or Mr. Bridgewater to keep Mr. Bennett from qualifying for the primary election on June 22, where Mr. Bennett’s advantages in name recognition and fund-raising could be decisive.

The Senate seat is not expected to change party hands in November, since Utah has not had a senator from the Democratic Party since the 1970s.

The convention itself functioned rather like the television show “Survivor” — sudden death for the candidate voted off the island.

With three rounds of voting, all but the top three candidates were eliminated after the first round. Delegates then voted a second time, whittling down the field again — that was where Mr. Bennett lost, coming in third with about 27 percent of the delegates’ support. A final round determines whether a primary election needs to be held. A candidate needs at least 60 percent of the vote to become the party’s candidate, and at least 40 percent to qualify for the primary election on June 22.

The state’s party chairman, Dave Hansen, in his opening remarks, acknowledged the huge numbers of first-time delegates, and the intense passions and anger that have infused moments of the campaign season heading into the convention.

“A lot of you have come here today with booing in your heart,” he said. He asked delegates to cheer their favorite candidate only, and not to disparage others, and for the most part they complied.