Jacob Rees-Mogg begged Boris Johnson-backing Tories to support Rishi Sunak until the next election “or we will be toast”.
The former Commons leader told a right-wing conference in Bournemouth that the party already looked “ridiculous” for changing leader twice.
And he said they would look “absurd” to do it again.
He was speaking at the inaugural conference of the Conservative Democratic Organisation, branded a “party within a party” and compared to a Tory version of Jeremy Corbyn-backing pressure group Momentum.
Mr Rees-Mogg, Priti Patel, former Northern Ireland Secretary Conor Burns and former Culture Secretary Nadine Dorries are guests of honour at the day-long get-together.
Disgruntled right-wing Conservatives from across the country, many frustrated with the direction their party is taking under Rishi Sunak, descended on the seaside destination to debate ways to "take back control" of the Tories.
Ms Jenkyns, a trained opera singer who infamously gave anti-Boris protesters the middle finger after he was deposed, opened proceedings by singing the national anthem, as delegates stood to attention and sang along.
Chairman David Campbell Bannerman, who arranged a "put Boris on the ballot" campaign after Mr Johnson was ousted last year, gave an opening speech, reassuring delegates: "You members are not smelly, or embarrassing as certain people think. You're not swivel-eyed loons."
He complained that under Mr Sunak: "The party is dying as an institution, we've got to invigorate it."
And he questioned the legitimacy of Mr Sunak's rise to power, replacing Liz Truss without a vote of members.
He said: "I think that has caused problems, because we haven't had the strong roots. There should have been a confirmatory ballot as far as I'm concerned."
In his keynote address, Mr Rees-Mogg complained about Mr Johnson, “our most successful electoral asset was removed without even a by-your-leave from the members.”
He said: “Many of us were very unhappy about what happened last year, and the changes of leader.
“But think very carefully. We must not change leader again. We must support Rishi Sunak to the general election, or we will be toast.
“Because any party that changes leader twice in a year falls in the opinion polls and looks ridiculous.
“If we were to do it again, how would we motivate anyone to vote for us on the basis that practically every member of the Conservative Party has been leader for a day.
“It would make us look absurd.”
He added: “We really do, in the interests of Conservative Democracy, have to support our current leader, in the current circumstances, and to the next election.”
