London (AFP) - Prime Minister Theresa May's cuts an increasingly lonely figure after her decision this week to turn to opposition leader Jeremy Corbyn to break the Brexit deadlock sparked a torrent of criticism from Conservatives.

The beleaguered leader wrote to Tory MPs on Wednesday to insist that several dozen Tories' stubborn resistance to her EU divorce deal had left her with little choice but to look to Labour for support.

Britain is set to crash out of the European Union at the end of next week if it has not passed May's withdrawal agreement or found a viable alternative plan.

"This is the only way to deliver the smooth, orderly Brexit that we promised," May said in her letter, in which she also reneged on previous pledges to leave without a deal if necessary.

The outreach to veteran leftist Corbyn, a reviled figure among British Conservatives and right-wingers who label him a Marxist, has drawn fury from eurosceptics in her party.

Corbyn wants to maintain closer ties with the EU than May through customs union membership and close alignment with the bloc's single market.

That is anathema to Brexiteers, with lawmaker Mark Francois telling her "Jeremy Corbyn is not our friend" and former Conservative leader Iain Duncan Smith MP accusing the prime minister of "betrayal".

"I fear for Brexit, it's never going to happen," he said.

Britain's right-wing newspapers joined in.

Tabloid The Sun labelled May a "traitor" on Thursday, while The Times said "she's like a prisoner on death row, getting another two-week reprieve.

"The truth is she is no longer in control of events," it added.

- 'Lost everybody' -

The hemorrhaging within May's government has been steady since the general election of June, 2017, which she called but which resulted in her party losing its parliamentary majority.

More than 30 ministers have resigned -- with two more departing this week in protest at her pivot toward Labour -- and the prime minister has been increasingly slow in replacing them.

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Downing Street on Thursday finally announced six new names for positions that had, in some cases, been vacant for weeks.

"Not even her cabinet can now look her in the eye," The Guardian columnist John Grace wrote.

"She has never been loved but there had been grudging respect for her resilience. Now there was just hatred."

Paul Breen, a senior lecturer at the University of Westminster, London, said May has "lost everybody" at this point.

But he reserves blame for David Cameron, her predecessor as PM who called the referendum on European Union membership in 2016 and then quit when the result went against him, and the Conservative Party.

"It's such a contentious issue they should have created some sort of... group of people like lawyers, economists, business people, to look at the different options," Breen said.

Instead, in the aftermath of the divisive poll, May set out a series of unnegotiable "red lines" on key Brexit issues in an apparent bid to please Brexiteers.

But when the overall deal failed to satisfy enough of these eurosceptics, her hardline stances came back to haunt her.

"She's like a football manager who has lost the dressing room," said Breen.

"Once that happens that's it, you're finished."