Former London Mayor Boris Johnson surprisingly announced on Thursday that he would not be joining the five other candidates seeking leadership of the Conservative Party. With this, the presumed front-runner in the race declined even to enter it.

"Having consulted colleagues and in view of the circumstances in parliament, I've concluded that person cannot be me," Johnson said in London, thanking his friends watching for their patience in waiting for the "punchline" to his speech.

"My role will be to give every possible support to the next Conservative administration to make sure that we properly fulfill the mandate of the people that was delivered at the referendum and to champion the agenda that I believe in, to stick up for the forgotten people of this country," Johnson said. He called the vote to leave the EU a chance for the UK "to think globally again."

His announcement came just hours after Michael Gove - thought by many to be a logical candidate to run alongside Johnson on an "all-Brexit" ticket - said he would be seeking the leadership role for himself.

Gove's potential candidacy became apparent on Wednesday, when an email from his wife "accidentally" landed in the public domain. In it, Gove's partner, Sarah Vine, urged her husband to demand "SPECIFICS" from Johnson before agreeing to run alongside him. She noted that conservative media moguls like Rupert Murdoch and Paul Dacre "instinctively dislike Boris but trust your ability enough to support a Boris-Gove ticket."

Rupert Murdoch - whose companies own Sky News and multiple UK daily papers - had congratulated Gove in February on his decision to betray his close personal friend Cameron and support "Leave."

On announcing his intentions earlier on Thursday, Gove said that Johnson "cannot provide the leadership for the task ahead."

Populist turned part-pariah

Johnson, the colorful former classmate of still-Prime Minister David Cameron at private school Eton College and then Oxford University, became the Leave campaign's most prominent supporter in the UK's EU referendum. He was criticized, however, for taking a side based on personal gain, with opponents pointing out that as recently as February, he had questioned the sense of holding an EU referendum at all.

In the aftermath of the surprise Brexit vote, Johnson had come in for further criticism, as he seemed to shy away from the limelight, occasionally appearing to issue reassurances that flew in the face of developments on the stock markets and currency exchange rates. His decision not to run elicited similar derision.

Johnson's political ambitions have been apparent since school. He was Eton's "Captain" and later the president of the Oxford Union debating society at university - both honors that evaded a young David Cameron. The two young Conservatives were also members of Oxford's notorious "Bullingdon Club," the upper-crust cabal of students known for rowdy evenings out at high-class restaurants.

A now-famous image of the Bullingdon Club's class of 1987, featuring both Johnson and Cameron in the group's hyper-formal uniform, has become a photo both Conservatives would likely love to see stricken from the record.

Michael Gove, Theresa May, Stephen Crabb, Liam Fox and Andrea Leadsom will contest the Conservative Party leadership - with a winner currently expected by September 9.