The Labour Party conference could vote to impose the mandatory re-selection of MPs, deputy leader Tom Watson has said.
Mr Watson said that while both he and Jeremy Corbyn opposed requiring MPs to face a vote of local party activists, he admitted they could not control the views of conference.
"We are both very much against mandatory re-selection but unfortunately that decision is made by our party conference," he told BBC Radio 5 Live's Pienaar's Politics.
His comments came amid fears among Labour moderates that some hard left supporters of Mr Corbyn want to introduce mandatory re-selection in order to purge them from the party.
Shadow culture secretary Michael Dugher warned that any such move would be "totally destructive" and risked plunging the party back into the bitter internal feuding of the 1980s.
"If you get into things like mandatory reselection you are heading down the Wacky Races road. We've played this game before and it doesn't end well. It's time to stop our punishment beatings," he told the Sunday Times.
While Mr Corbyn backed mid-term election for the leader during the leadership campaign, Mr Watson warned that MPs hoping to get rid of Mr Corbyn should not bank on the idea.
"I think it would be a mistake if MPs think that they should aim for that because I think it would undermine his leadership and destabilise the party," he said.
Despite his own policy differences with the leader, Mr Watson insisted that he had his full support and that any attempt by MPs to oust him was doomed to fail.
"If MPs feel very strongly about that they could put an MP up, but, I tell you what, I think that if they did put an MP up against Jeremy Corbyn he would win hands down," he said.
"He has my full support. We are a team in this and I am going to be working with him to make sure the Labour Party has an election-winning programme in 2020."
Mr Watson, who supports the renewal of Britain's Trident nuclear deterrent, acknowledged that he was at odds with Mr Corbyn on the issue and said it was "likely" MPs would have to be given a free vote when the issue comes to the Commons next year.
"We have very different views on Trident and the truth is we are just going to have to reach an accommodation on that," he said.
"It makes collective responsibility obviously different. I would have to do interviews where you know my private views but I explain the collective view of the party. Modern politics has got to be like this. You simply cannot have homogeneous positions where 200 people follow a line on everything."
Asked whether he could serve in a Labour government that was committed to scrapping Trident, he said: "We'd have to cross that bridge when we come to it."