Health Secretary Matt Hancock said that after the first round of voting it was clear he did not have the backing to win. He came fifth in a vote Thursday among 313 Conservative lawmakers, with 20 votes.
Johnson, a former foreign secretary, won Thursday's ballot with 114 votes, more than the next three candidates combined. Hancock did not say whom he planned to support. The 40-year-old had pitched himself as the face of a younger, modernizing generation in the Conservative Party, promising to deliver an energizing blend of social liberalism and economic dynamism. But his message failed to gain much traction in a party consumed with Britain's stalled departure from the European Union.
Hancock said he had run as the "candidate of the future" but found that "the party, understandably, is focused very much on the here and now and how we get through Brexit." The Conservative Party is holding a contest to replace Prime Minister Theresa May, who quit as party leader last week after failing to secure Parliament's backing for her divorce deal with the EU.
Tory legislators will hold more elimination votes next week, with the final two contenders put to a vote of 160,000 Conservative Party members nationwide. The winner, due to be announced in late July, will become Conservative leader and prime minister.
Johnson's commanding lead makes him almost certain to be in the final two. The flamboyant former London mayor is admired by many Conservatives for his ability to energize voters, but is also widely mistrusted for his record of misleading statements, verbal blunders and haphazard performance in high office.
Johnson has vowed that as prime minister he would "get Brexit done," either by renegotiating May's rejected Brexit deal or by leaving the EU on Oct. 31 without an agreement. But Johnson has not answered many tough questions about his plans. The EU says it will not reopen the divorce agreement, and many economists say a no-deal exit would cause economic turmoil.
All the remaining candidates, apart from Johnson, say they will take part in TV debates on Sunday and Tuesday. Johnson signaled he was unlikely to take part in Sunday's Channel 4 program, saying debates with "loads of candidates" could be "slightly cacophonous."
But he said he would take part in a BBC debate on Tuesday evening, once the field of candidates has been reduced by a second round of voting. Foreign Secretary Jeremy Hunt, who is in second place, said a prospective national leader should not be "hiding away from the media."
In addition to Johnson and Hunt, those still in the race are Environment Secretary Michael Gove, ex-Brexit Secretary Dominic Raab, Home Secretary Sajid Javid and International Development Secretary Rory Stewart.
Follow AP's full coverage of Brexit and the Conservative Party leadership race at: https://www.apnews.com/Brexit