In a statement outside No. 10 Downing Street before the vote, Ms.
If there are multiple candidates, Conservative MPs hold a series of votes to choose two to go forward to a vote of party members.
In a statement Sir Graham said: 'The votes will be counted immediately afterwards and the result will be announced as soon as possible in the evening'. "But this Prime Minister can not even do her own job because of the Tory civil war", he said.
May, who supported the campaign for Britain to remain in the E.U., has seen her time in office overshadowed by the question of Brexit as she has sought to keep her own party happy while also negotiating a deal with European leaders.
Many supporters of Brexit say May's deal, a compromise that retains close economic ties with the European Union, fails to deliver on the clean break with the bloc that they want.Former Environment Secretary Owen Paterson accused May of acting like a "supplicant" in dealings with the EU.
Brexit-backing International Development Secretary Penny Mordaunt posted: "The Prime Minister has my full support, not least because she has always done what she firmly believes is in the national interest".
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There was confusion at Westminster on Monday over whether the 21 January deadline applied, as a withdrawal deal has been reached. Speaking to LBC live from Westminster, Jenny Chapman said "it's going to happen, it's on its way".
Wednesday's ballot was announced after more than 15 percent of Conservative MPs wrote to the party's backbench parliamentary committee demanding a say on May's leadership of the party, breaching a required threshold and activating the poll.
The Prime Minister is expected to spend Wednesday battling to win the favour of her MPs.
Cabinet ministers, including some widely-tipped as potential successors to the prime minister, quickly took to the airwaves in a concerted show of support.
All 315 Tory legislators can vote on the confidence motion. But our party will rightly not tolerate it.
"The only thing that seems clear is this decision to trigger a leadership election at this time could be potentially disastrous for the Conservative Party's electoral fortunes".
Lead Brexiteer Jacob Rees-Mogg said May should go to the Queen and tender her resignation.
May had staged a late battle to save her job, her European Union divorce bill and maybe even Brexit itself as lawmakers in her Conservative Party held a no-confidence vote on her leadership.
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Even in Madrid , they are humble but here, I feel they are more so. "For me, it is handsome , to feel that difference". I like the city, the people and the club. "I couldn't be 100 per cent sure I was joining the best club in the world".
May said before the vote that it was "now clear" the backstop needs to be temporary, and that she was confident she could still win approval in Parliament for her withdrawal plan with further assurances from the EU.
The former Northern Ireland secretary and prominent Brexiteer said she had become a "blockage" to an agreement which Parliament and the country could support.
"Weeks spent tearing ourselves apart will only create more division", she said. None of that would be in the national interest. "The public want us to sort £Brexit now!"
"The Prime Minister has lost her majority in Parliament, her government is in chaos and she is unable to deliver a Brexit deal".
The pound fell briefly in response to news of the challenge to Mrs May, but later rallied.
May cancelled a trip to Dublin on Wednesday for talks with Irish Prime Minister Leo Varadkar amid the leadership challenge.
'The government need to be putting the country first and providing real leadership at this time of constitutional crisis.
The BBC's Political Editor Laura Kuenssberg said a delay to Brexit was "a vital part of the case the prime minister's supporters will be making" as she faces the confidence vote.
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Luiz said he felt Chelsea had beaten "the best team in Europe at the moment". Two Premier League left-backs are being targeted by Marseille.