Several hopefuls vying to replace British Prime Minister Theresa May turned their fire on favorite Boris Johnson on Sunday, questioning his pledge to leave the European Union by the end of October no matter what.

With former London mayor and foreign minister Johnson keeping a low profile, the other candidates have targeted the airwaves to present their cases to lead the governing Conservative Party. But the question always returns to "Boris."

At a Channel 4 debate, his absence was marked by an empty lectern. That left the five other candidates to argue over which man was best placed to deliver Brexit in testy exchanges International Development Minister Rory Stewart described as a competition of "machismo."

They questioned his ability to navigate Britain's departure from the EU, saying his pledge to leave on October 31 was nigh on impossible and would set Britain on track for a no-deal Brexit.

In his weekly Telegraph newspaper column, Johnson ignored the criticism over his absence, instead turning his attention to the "digital divide" in Britain.

Almost three years since Britain voted to leave the EU, the country, parliament and both main parties are still deeply divided over how, when and even whether Brexit should happen.

Brexit has claimed two prime ministers. David Cameron resigned shortly after a 2016 referendum, and now May is making way for a successor because of her failure to get a deal she agreed with the EU through parliament.

Brexit is dominating the Conservative leadership race, with several of the candidates, albeit some of them reluctantly, saying they would lead the nation out without a deal.

Rory Stewart, who wants to rule out a no-deal Brexit, took issue with the argument of Johnson and other candidates that the only way to get an improved deal from the EU was to prepare for leaving without an agreement and use that as leverage.

"They are not scared of it because it is not a credible threat. The European Union knows no deal cannot get through parliament," said Stewart, a relative unknown who has shot up the bookmakers' odds to be placed second.

"How is Boris going to deliver Brexit, how? ... 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. We want to know what he believes."

Conservative MPs will hold successive rounds of voting from Tuesday to reduce the candidates to just two, then 160,000 grassroots party members will pick the winner in a postal ballot.

The victor, who will become Britain's next prime minister, is set to be announced in the week starting on July 22.

Johnson topped last week's first round with 114 votes, ahead of Hunt on 43 and Gove on 37. Raab got 27, Javid got 23 and Stewart was on 19.

The survivors of the second round on Tuesday will face a BBC television debate later the same day, which Johnson has said he will attend.

(With input from Reuters and AFP)

(Cover: PM candidates Jeremy Hunt and Rory Stewart appear on BBC TV's The Andrew Marr Show, June 16, 2019. /Reuters Photo)