(Bloomberg) -- U.K. Prime Minister Theresa May vowed one more push to get her unpopular divorce deal through Parliament but her party is already moving on, hurtling into a bitter leadership race that will define the course of Brexit.

Rival factions of the Conservative Party are staking out their positions and on Monday Work and Pensions Secretary Amber Rudd will lead a group of 60 Tories seeking to stop bookmakers’ favorite Boris Johnson from succeeding May and pursuing a chaotic no-deal exit from the European Union.

The contest to succeed May is all but under way even as the prime minister continues to fight what appears to be a futile battle to get her Brexit deal over the line -- she has promised to put a date on her departure after giving it a fourth and probably final shot in Parliament in June. The government will make a “bold new offer” to improve the deal this week, May said on Sunday, after talks aimed at a cross-party consensus collapsed.

But pessimism is growing over whether May will be able to win over enough MPs. A leaked document seen by the Telegraph suggests her new plan is just a “retread” of old ideas. Any concessions aimed at Labour members of parliament are likely to erode support among those on her own side.

In a sign that the differences between the government and opposition Labour Party over Brexit are getting even harder to bridge, Labour leader Jeremy Corbyn on Sunday went the furthest yet in his support for a second referendum. May has repeatedly rejected going back to the public again.

So May’s colleagues are focusing on who will replace her.

Rudd’s new “One Nation Caucus,” which seeks to block a candidate who supports no-deal, includes at least seven Cabinet ministers, according to the Daily Mail. Separately, Chancellor Philip Hammond this week will warn leadership hopefuls against pursuing populist policies or Brexit outcomes that don’t command a majority in parliament, such as no-deal.

The Tories are preparing to choose a new leader as their party braces for a humiliating rout in European elections on May 23. May never wanted to take part in the ballot, but her failure to get a deal done and the two sides’ decision to extend the deadline twice left her with no choice.

The Brexit party, founded by veteran anti-EU campaigner Nigel Farage, is leading opinion polls, with 34% in the latest Opinium survey for the Observer on Sunday. The Tories were trailing fourth at 12 percent.

In other developments:

  • Brexit Secretary Stephen Barclay refused to rule himself out of the leadership race when asked on Sky’s Sophy Ridge show.
  • Corbyn said putting an end to freedom of movement after Brexit was negotiable, backing away from an earlier pledge.
  • May said in the Sunday Times the Cabinet will consider whether holding votes in Parliament to test support for Brexit alternatives would be a "useful prelude" to a vote on her deal

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, Emma Ross-Thomas, Colin Keatinge

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