Brexit backer Boris Johnson rules out run to become Britain's next prime minister

Boris Johnson, the former mayor of London who supported the "leave" campaign in the U.K.'s referendum on whether to cut ties with the European Union, said Thursday he won't seek to become the new leader of the ruling Conservative Party. "I have concluded that person cannot be me," said Johnson during a press conference. Johnson had widely been expected to join the leadership race that would have put him in contention to become Britain's next prime minister. Britain's Prime Minister David Cameron, who campaigned to keep the U.K. in the EU, said after his side's defeat last week that he will resign.

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