Boris Johnson has pulled out of the Conservative leadership race.
Mr Johnson had the public backing of 59 Tory MPs but had to reach 100 to proceed in the race.
This leaves the race open for former chancellor Rishi Sunak who leads nominations among Tory MPs, with 144 supporters.
In a statement, the former prime minister confirmed that he had "cleared the very high hurdle of 102 nominations", but came to the conclusion that "this is simply not the right time".
In reaction to his statement, Nadhim Zahawi said "a day is a long time in politics", and said he was now supporting Rishi Sunak, just 12 hours after he tweeted that he would back Mr Johnson.
So far, Mr Sunak leads with backing with more than 140 supporters, while Penny Mordaunt is on 24. The candidates must secure the backing of 100 MPs by 2pm tomorrow to go forward in the race.
On Sunday, several long-time allies of Mr Johnson, including Suella Braverman and Steve Baker, threw their support behind Rishi Sunak, the frontrunner in the race.
He added: "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".
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Mr Johnson said while he was "attracted" to support from his colleagues, he added "you can't govern effectively unless you have a united party in parliament".
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 did receive the backing of Tory MPs including Foreign Secretary James Cleverly and Mr Zahawi, the Chancellor of the Duchy of Lancaster.
