Boris Johnson rejects 'white flag' of Brexit delays

UK leadership race frontrunner Boris Johnson insisted Friday he would never raise the "white flag" of surrender and plead for a further delay of Brexit if no EU deal was ready by October 31.

The former foreign minister also said he would replace the controversial "backstop" solution for keeping the Irish border open after Brexit with advanced technological checks along the new EU frontier.

He also bowed to growing political pressure and agreed to debate the other Conservative Party contenders to replace outgoing Prime Minister Theresa May on BBC television Tuesday evening.

The field of hopefuls to take on one of the most challenging political assignments in Europe narrowed to six on Friday after Health Secretary Matt Hancock withdrew.

But the odds-on favourite is Johnson -- a figurehead of the 2016 referendum that triggered the laborious process of extricating Britain from the European Union after nearly 50 years.

Johnson said London could finally get what it wanted once it made abundantly clear to Brussels that it could walk away without a deal.

"We've got to be out by October 31," Johnson told BBC radio in one of his most extensive public interviews since May resigned last month.

"Unless we show fortitude and determination, I don't think we will carry conviction in Brussels about the deal we want to do."