Johnson, a former foreign secretary who has run a deliberately low-profile leadership campaign, was accused of trying to avoid scrutiny after he refused to take part in a televised debate Sunday night among the six candidates still in the race.
An instantly recognizable figure, famous for his Latin quips and unruly blond hair, Johnson is admired by many Conservatives for his ability to energize voters. But others mistrust him for his long record of misleading and false statements, verbal blunders and erratic performance in high office.
International Development Secretary Rory Stewart, one of the contenders, said there was "a problem of trust" with Johnson. "Who do you trust to be your prime minister?" Stewart told the BBC. "How is Boris going to deliver Brexit? He keeps saying 'I am going to deliver it.' I don't even know what he believes. He won't talk to me. He won't talk to you. He won't talk to the public."
Johnson, a former London mayor, has a commanding lead after last week's first round of voting by Tory lawmakers in the contest to replace Theresa May. She stepped down as party leader earlier this month after failing to secure Parliament's backing for her European Union divorce deal.
He got another boost Sunday, gaining the backing of Esther McVey, one of three candidates eliminated race last week. The 313 Tory lawmakers in the House of Commons are set to narrow the field of candidates in a series of votes this week, with the final two names put to a postal vote of about 160,000 Conservative members nationwide.
The winner, who will become party leader and prime minister, is due to be announced in late July. But some in the party say the membership vote could be skipped if Johnson is so far ahead that he looks unlikely to be beaten.
Others argue that would be a big mistake. May became prime minister in 2016 without a party vote, after all her rivals dropped out of the race. Critics say a more robust contest would have exposed her flaws as a leader before she got the top job.
Home Secretary Sajid Javid, who is also running, said that "as Conservatives, we should embrace competition over coronation." In addition to Johnson, Javid and Stewart, other contenders include Foreign Secretary Jeremy Hunt, Environment Secretary Michael Gove and ex-Brexit Secretary Dominic Raab.
The leadership contest has been dominated by the topic of Brexit, with all the candidates promising to succeed where May failed and lead Britain out of the EU. The U.K. was originally due to leave the bloc on March 29, but Brexit has been delayed to Oct. 31 because of the political deadlock in London.
Johnson has won support from many Brexit-backing Conservatives by vowing to "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 avoided answering tough questions about his plans. The EU says it will not reopen the Brexit divorce agreement, and many economists and businesses say a no-deal exit would cause economic turmoil by ripping up the rules that govern trade between Britain and the EU.
Critics also say Johnson's political record is tainted by blunders and outright lies. During the country's 2016 EU membership referendum, he campaigned on the inaccurate claim that Britain sends 350 million pounds ($444 million) a week to the EU.
In 2017, when he was foreign secretary, he said incorrectly that a British-Iranian woman imprisoned in Iran was a journalist, damaging attempts to secure her release. His language has also frequently given offense. Johnson has called Papua New Guineans "cannibals," referred to people in Commonwealth countries with the offensive term "piccaninnies" and last year compared Muslim women who wear face-covering veils to "letter boxes."
Last week Johnson apologized for any offense his words had caused, but also claimed they had often been taken out of context. Johnson has given few media interviews since he began his leadership campaign, and declined to take part in Sunday's Channel 4 debate alongside all the other candidates. He has agreed to participate in a BBC debate on Tuesday, once the field of candidates has been reduced by a second round of voting earlier in the day.
Defense Minister Tobias Ellwood said Sunday that so far Johnson "seems to be the runaway winner." "But the question is, though, do we just allow him to walk across to the touchline and put the ball down and have that coronation? I don't think that's right," Ellwood told Sky News. "I actually want to see Boris tested. The nation is watching this."
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