He announced this on Twitter.
“It was not an easy choice, but I am focused on my current job and ensuring the security of this great country,” the minister wrote, quoted by Sky News.
As previously reported by the media, the main contender for Johnson's seat is Secretary of Defense Wallace.
On July 7, Boris Johnson announced that he had decided to step down as Prime Minister of Great Britain and leader of the country's Conservative Party.
He will continue to fulfill his duties until the election of a new head of the cabinet of ministers.