Boris Johnson says he had enough support among the party's MPs to seek the nomination, but that he has come to the conclusion that "it is not the right thing to do" and that "you cannot govern effectively unless the party is united in Parliament”.

Requires the support of 100 members

Sky News reports that 59 Conservative MPs have publicly expressed their support for Johnson, he himself says that 102 MPs have expressed their support for him.

In order to enter the fight for the role of party leader, the support of at least 100 members is required.

- My assessment is that Boris Johnson had run if he thought he could have won, but he judged that it was not possible, says James Savage, editor-in-chief of The Local newspaper.

Sunak likely leader

According to the BBC, Rishi Sunak, who was previously finance minister, has secured the support of 147 members.

He is 42 years old and a Member of Parliament since 2015.

- Rishi Sunak has a very large advantage and I would think that it is basically clear that he will become the new prime minister, says SVT's foreign reporter Anna-Maja Persson.

- Now the Tory Party will unite behind Rishi Sunak, says James Savage.

Penny Mordaunt, former defense minister, is also running for nomination.

However, she only has the support of 24 members, according to the BBC.