Jeremy Hunt has called on his Tory leadership rival Boris Johnson to stop being a “coward” and face him in a live head to head TV debate.
The foreign secretary accused Mr Johnson of trying to become prime minister by “slinking through the back door” of Number 10 after he declined to take part in a debate on Sky News.
Mr Hunt also said that he feared a government led by Mr Johnson would rapidly collapse, because he would be unable to hold together a coalition of supporters that range from MPs who back no deal to others who feel it would be totally unacceptable.
“If you are not clear about exactly what you are going to do, that coalition will collapse immediately and you will have Corbyn in Number 10”, he said in a Times column.
Mr Johnson meanwhile used his weekly column in the Daily Telegraph to reaffirm his commitment to deliver Brexit by the end of October in an apparent attempt to refocus attention away from his private life.
He wrote: “We must leave the EU on October 31 come what may. It will honour the referendum result, it will focus the minds of EU negotiators.
“We are just over four months away from the date on which, by law, we must leave the EU, and this time we are not going to bottle it. We are not going to fail.
“This time we are not going to shrink in fear from the exit, as we have on the last two occasions.”
The comments came as north-east MPs Ross Thomson, Colin Clark and Douglas Ross reaffirmed their commitment to Mr Johnson.
In a joint letter published online they said: “Iconic Aberdeen granite forms the foundational underpinning of the Palace of Westminster.
“In the same way, Scotland provides a foundational keystone to what Boris has referred to as the “awesome foursome” – our United Kingdom.
“It’s clear to us that a Boris Johnson premiership would have the future of our Union at its heart.”
They added: “Along with the over one million Scots who voted Leave – including 400,000 SNP supporters – many in the north-east wanted, like us, to leave the Common Fisheries Policy to breathe life back into our coastal towns.
“We are backing Boris in order to get Brexit done then move on to deliver a strong, one-nation Conservative policy agenda for the future.”
The Tory leadership contenders will be journeying across the UK over the next month to speak at series of hustings with party members, who will ultimately decide who becomes Britain’s next prime minister.