Foreign Secretary Liz Truss has officially joined the race for the Tory leadership, with Home Secretary Priti Patel potentially set to announce her candidacy.
A surprise entry has also been made by Foreign Office minister Rehman Chishti, meaning 11 Conservatives are now fighting to replace Boris Johnson as prime minister.
Writing in the Telegraph newspaper, Ms Truss pledged to “start cutting taxes from day one” with a commitment to reverse April’s National Insurance rise.
A supporter of Home Secretary Priti Patel said there was a “strong chance” she would put herself forward as well.
Another ally said Ms Patel was still considering her position but added that she had more support than some of the candidates who had already publicly declared.
Launching his campaign with a video on Facebook, Mr Chishti said: “For me, it’s important to ensure everyone who works hard, who’s determined, who perseveres, that they have a government that is on their side, and that means lower taxes, small state, big society.”
On Monday, party elders on the 1922 Committee of Tory MPs will decide the rules under which the leadership contest will be held.
With so many people standing, there is pressure for the process to be sped up to ensure only MPs with sizeable levels of support can get onto the ballot paper.
It’s hoped MPs will whittle down the candidates to the last two in the coming days before party members make the final choice over the summer.
This would allow the new prime minister to be in place by the time parliament returns in September.
Communities minister and “next generation” candidate Kemi Badenoch had a boost to her campaign after winning the backing of former cabinet minister Michael Gove.
Chair of the Northern Research Group of Tory MPs, Jake Berry, said he would be voting for Tom Tugendhat.
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Ms Truss had been widely expected to run for the top job and pointed to recent controversial Brexit legislation as one of her key achievements.
“I am putting myself forward because I can lead, deliver and make the tough decisions,” said the foreign secretary in her Telegraph article.
She is one of several contenders promising big tax cuts if elected.
Ms Truss has already received the backing of Kwasi Kwarteng, with the business secretary telling The Sun that the UK would enjoy a new era of tax cuts and business investment under her leadership.
On Saturday, former health secretary Sajid Javid pledged to reverse the National Insurance rise and cut corporation tax if he makes it to Downing Street.
There’s also been scrutiny of the business backgrounds of some candidates with Chancellor Nadhim Zahawi claiming he had been subject to “smears” over newspaper claims relating to his tax affairs.
Speaking to Kay Burley, the former businessman pledged to publish his accounts annually if elected Tory leader.