London (CNN) Boris Johnson, the favorite to succeed Theresa May as British Prime Minister, has refused to rule out firing the UK ambassador to Washington who provoked the ire of US President Donald Trump.

In a televised debate on Tuesday, UK Foreign Secretary Jeremy Hunt, who is standing against Johnson for the leadership of the Conservative party, reiterated his support for Kim Darroch, who was revealed in leaked cables to have criticized Trump as "inept" and "incompetent," among other things. "I will keep [Darroch] until he's due to retire," he said.

Johnson, a former Foreign Secretary, refused to go out on a limb about whether he would decide to keep Darroch on. "I won't be so presumptuous as to assume that I'm going to be in a position to take that," he said.

"It is vital that our civil service is not politicized by people leaking what they say," Johnson also said. "Whoever leaked that deserves to be eviscerated."

Johnson is currently seen as the frontrunner in the race, after May was effectively toppled by her own lawmakers for failing to deliver on Brexit. He is expected to seek to forge a much closer relationship to Trump than May, who made strenuous efforts to court the President and developed a respectful relationship but never really bonded with him politically.