Rishi Sunak will be the UK’s next prime minister after Penny Mordaunt withdrew from the contest.
Ms Mordaunt had been the only other MP left in the race after Boris Johnson dramatically withdrew on Sunday night.
But she faced an uphill battle to secure the 100 nominations needed to stay in contention.
She had just 24 declared supporters.
By mid-morning the writing appeared to be on the wall, when one of those, former minister George Freeman, appeared to openly call on her to pull out for the sake of party “unity”.
Team Morduant battled on however, claiming that they had now secured 90 supporters, although the list of those who backed her publicly barely rose.
In a statement on Twitter, Ms Mordaunt said it was clear that MPs felt “we need certainty”. She added: “They have taken this decision in good faith for the good of the country.
“Members should know that this proposition has been fairly and thoroughly tested by the agreed 1922 process.
“As a result, we have now chosen our next Prime Minister. This decision is an historic one and shows, once again, the diversity and talent of our party. Rishi has my full support.
“I am proud of the campaign we ran and grateful to all those, across all sides of our party, who gave me their backing.
“We all owe it to the country, to each other and to Rishi to unite and work together for the good of the nation. There is much work to be done.”
Ms Mordaunt’s supporters expressed dismay and suggested that they could have reached the 100 vote threshold if they had had more time.
The leadership race was hastily arranged after the shock resignation of Liz Truss last week.
Ms Mordaunt’s withdrawal means that what was a contest has become a coronation and Mr Sunak is expected to become prime minister on Tuesday.
But opposition parties said a coronation was “antidemocratic” and demanded a general election, as pressure mounts on the government to give voters a say.
Lib Dem leader Ed Davey said Tory MPs had “installed another out-of-touch prime minister with no plan to repair the damage and without giving the British people a say”.
The SNP has said the Tories “cannot be allowed to impose a third prime minister without a general election”, while Plaid Cymru’s Westminster leader Liz Saville Roberts said: “The antidemocratic nature of the Westminster system has been laid bare for all to see. Rishi Sunak has no mandate, no legitimacy. Democracy demands a general election.”
Caroline Lucas, the Green Party MP, said it was “difficult to think of a prime minister with less of a mandate to govern than Rishi Sunak, our fifth in six years – a man who was resoundingly rejected less than two months ago by Tory members”.
Mr Sunak is to address Tory MPs at 2.30pm.