(Bloomberg) -- Jeremy Corbyn, leader of the U.K.’s opposition Labour Party, asked rival parties to support him as prime minister in a coalition to block Boris Johnson’s government from pursuing a no-deal Brexit.

Corbyn wrote to other political parties’ leaders and rebels in the Conservative Party Wednesday, seeking support in a vote of no confidence in the government. He said that if that was successful, they should make him caretaker prime minister so he could delay Brexit and call a general election.

Johnson has said he’s committed to delivering Brexit “do or die” on Oct. 31. He insists the European Union must reopen the deal negotiated by his predecessor, Theresa May, and remove a section designed to prevent a hard border between the U.K. and Ireland but which he regards as trapping Britain in the bloc’s orbit. The prime minister has said he’s ready to leave without a deal if necessary, something economists say would harm the economy.

Members of Parliament seeking to stop a no-deal split have floated plans including replacing Johnson with a cross-party “government of national unity” to seek a Brexit delay. But Corbyn’s insistence that he should lead that administration shows the problem with this idea.

“Following a successful vote of no confidence in the government, I would then, as Leader of the Opposition, seek the confidence of the House for a strictly time-limited temporary government with the aim of calling a general election, and securing the necessary extension of Article 50 to do so,” Corbyn wrote.

Reluctant

Even Tories who are vehement opponents of Brexit would struggle with the idea of making the most socialist leader Labour has had in decades prime minister.

“Jeremy Corbyn is not the person who is going to be able to build an even temporary majority in the House of Commons for this task,” Liberal Democrats leader Jo Swinson said in an emailed statement. “This letter is just more red lines that are about him and his position and is not a serious attempt to find the right solution and build a consensus to stop a no-deal Brexit.”

It’s also possible some Labour MPs would resist -- nine have left the party this year in protest at Corbyn’s leadership. But Corbyn’s proposal confirms that he wouldn’t allow Labour MPs to support any other such government.

His letter also signaled that a confidence vote might not come the moment Parliament returns at the start of September. Corbyn said he would call one “at the earliest opportunity when we can be confident of success.” That would mean waiting for a sign that at least one Conservative MP was willing to vote against his own government -- an act from which there would be no return.

Election?

If Johnson did lose a confidence vote, a 14-day period would follow in which someone else could try to form a government, or he could try to win a new confidence vote. An election would be triggered if those efforts failed.

Other plans are underway to stop the U.K. leaving the EU without an agreement. On Wednesday, former Chancellor of the Exchequer Philip Hammond warned Johnson he’ll work with other ex-ministers to try to stop a no-deal Brexit, which he called a “betrayal” of the 2016 referendum result.

Johnson replied that such moves were undermining his attempts to get the EU to shift. “There’s a terrible kind of collaboration -- as it were -- going on between people who think they can block Brexit in Parliament and our European friends,” Johnson said in a Facebook Live broadcast.

Corbyn sent his letter to three members of the Conservative Party who have led efforts to block a no-deal Brexit -- Dominic Grieve, Oliver Letwin and Caroline Spelman. He also wrote to the leaders of the Scottish National Party, Liberal Democrats, Plaid Cymru and the Green Party. He didn’t include former Labour MPs who quit the party, whose votes he would also likely need.

‘Non-Committal’

The Labour leader last week asked the U.K.’s most senior civil servant, Cabinet Secretary Mark Sedwill, for an assurance that if an election were called, Brexit would be delayed until after polling day. Corbyn on Wednesday described Sedwill’s response as “non-committal.”

Responding to the Labour proposal, a spokesman for Johnson said voters now faced “a clear choice” between Johnson and Corbyn as prime minister.

“This government believes the people are the masters and votes should be respected,” he said. “Jeremy Corbyn believes that the people are the servants and politicians can cancel public votes they don’t like.”

To contact the reporter on this story: Jessica Shankleman in London at jshankleman@bloomberg.net

To contact the editors responsible for this story: Tim Ross at tross54@bloomberg.net, Robert Hutton, Stuart Biggs, Mark Williams

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