LONDON -- Boris Johnson solidified his front-runner status in the race to become Britain's next prime minister on Tuesday, gaining backing from leading pro-Brexit lawmakers.
But he faced calls from his rivals to abandon his low-profile campaign strategy and start answering questions from journalists and the public.
Ten candidates are running to succeed Theresa May, who stepped down last week as Conservative Party leader.
Johnson, 54, has won the backing of many Brexiteer Conservatives by promising to lead Britain out of the European Union by Oct. 31, with or without a divorce deal.
Brexit-backing ex-party leader Iain Duncan Smith wrote in Tuesday's Daily Telegraph that Johnson "is the most likely to deliver on the requirement to leave the EU" by that date.
Johnson has also been endorsed by some pro-EU Tories who think the flamboyant, tousle-haired ex-foreign secretary has the skills to energize a demoralized party and win back voters angry at the mess politicians have made of Brexit.
In a straw poll among a right-of-center bloc of Tory lawmakers on Monday, Johnson received almost double the votes of his nearest rival.
Most have given television and radio interviews and held public launch events — things Johnson has so far avoided, in an attempt to reduce the chance of gaffes that could derail his campaign. He also has not said whether he will participate in planned televised debates among leadership candidates.
The right-leaning Daily Mail newspaper said in an editorial that "if he wants to win, this bunker mentality is simply not good enough. Even though he's the favorite, he can't just sit back and hope to win by default."
Health Secretary Matt Hancock, another contender, said "everybody who puts their name forward to be prime minister should be open to scrutiny, should be accountable."
"I think everybody should participate in the proposed TV debates and I think we have got to ask the question, why not?" he told the BBC.
May resigned as Conservative leader last week after failing three times to secure Parliament's backing for her divorce deal with the EU. She'll remain caretaker prime minister until the party chooses a replacement.
The candidates to succeed her divide between those, including Johnson, who say the U.K. must leave on the scheduled date of Oct. 31, and others willing to delay departure in order to secure a divorce deal that's acceptable both to the EU and to Parliament.
"It is not going to be possible to leave on the 31st of October," said candidate Mark Harper, who said more time would be needed to secure a reworked deal with the EU and get it through Parliament.
But former House of Commons leader Andrea Leadsom put herself firmly in the hard Brexit camp, saying that "leaving the EU on October 31 is for me a hard, red line."
In votes starting Thursday, the 313 Conservative lawmakers will narrow the field of 10 candidates down to two, who will be put to a vote of about 160,000 party members nationwide.
The winner, who will become Britain's next prime minister, is due to be announced in late July.