Boris Johnson has pulled out of the Conservative leadership race.
His withdrawal leaves the path to No 10 open to Rishi Sunak.
The former prime minister had the public backing of 59 Tory MPs but had to reach 100 to proceed in the race.
Mr Sunak, the former chancellor, has more than 140 backers, a significant lead over Penny Mordaunt, the only other remaining candidate.
Path to No 10 opens for Sunak – live updates
In a statement, Mr Johnson said he had “cleared the very high hurdle of 102 nominations”, but came to the conclusion that “this is simply not the right time”.
He said: “And though I have reached out to both Rishi and Penny – because I hoped that we could come together in the national interest – we have sadly not been able to work out a way of doing this.”
Mr Johnson said that although he was “attracted” to run because of the support from his colleagues, “you can’t govern effectively unless you have a united party in parliament”.
The first Johnson backer to publicly switch to Mr Sunak was Nadhim Zahawi, the former chancellor, who tweeted “a day is a long time in politics”.
He came out for Mr Johnson this morning.
Ms Mordaunt, the leader of the Commons, has the public backing of 24 MPs. She needs 100 by 2pm tomorrow to stay in the race.
On Sunday, several long-time allies of Mr Johnson, including Suella Braverman and Steve Baker, threw their support behind Mr Sunak.
Boris Johnson’s withdrawal casts doubt he ever had the numbers
Boris Johnson never officially entered this campaign, but make no doubt about it he has been running a campaign to re-enter Number 10
One of the oddities of this campaign though has been that his allies and people that were working on that campaign with him have been briefing journalists and saying publicly that he had the numbers to get on to the ballot tomorrow.
Now if that was true, that would have meant that the competition was essentially sewn up for him.
Because that would mean that the next stage is the party members and we know that he was a big favourite with Conservative Party members.
I think there’s now a question mark over that claim that he had those 100 backers in the Conservative Party was ever true.
This very much leaves the path open now for Rishi Sunak to take over in Number 10.
Mr Baker, the former head of backbench Brexiteers, warned that a potential comeback by Mr Johnson would be a “guaranteed disaster”.
Mr Sunak had already met the threshold needed to make it to the next stage of the race before his candidacy announcement this morning.
Mr Johnson flew back from a holiday in the Caribbean on Saturday and did not formally announce his candidacy in the race.
He secured the public backing from big names in the cabinet, including Foreign Secretary James Cleverly and Mr Zahawi, the chancellor of the Duchy of Lancaster.