Per the Guardian:

Boris Johnson will not stand in the Conservative Leadership race, leaving Rishi Sunak very likely to enter No 10.

The former prime minister had not formally declared but he had told supporters he wanted to run, drumming up backing from seven cabinet ministers – Jacob Rees-Mogg, James Cleverly, Anne-Marie Trevelyan, Nadhim Zahawi, Alok Sharma, Simon Clarke and Chris-Heaton Harris.

After cutting short a Caribbean holiday, Johnson spoke to rivals Sunak in an attempt to persuade them to get on board with his attempted political comeback.

However, Johnson has said he is not running after only making it to about 60 declared backers by Sunday evening – well short of the 100-MP threshold required to make it on to the ballot.