Sadiq Khan said “bring it on” when he was asked to comment on speculation that Boris Johnson might stand against him at the next City Hall election.
Mr Johnson has been rumoured to be considering a bid to stand for his old job as London mayor, after he announced that he was standing down as an MP.
Speaking with James O’Brien on LBC, Mr Khan threw down the gauntlet to his predecessor.
The mayor was asked by one listener: “Would you be worried if Boris Johnson became a London mayoral candidate?”
Mr Khan replied: “The flippant answer is bring it on.”
Mr Johnson served as mayor from 2008 until standing down in 2016, when Mr Khan took over.
The Labour mayor is now running for a historic third term. The Conservatives have selected a shortlist of three people, who are currently battling it out to be selected as the party’s candidate in May 2024.
If Mr Johnson plans on running, therefore, he will have to do so as an independent, or join another party.
One of the shortlisted Conservative candidates, Moz Hossein KC, was asked in a recent interview for his thoughts on Mr Johnson standing.
“If he wants to, then he should,” said Mr Hossein.
“This is the exciting thing about London – anybody, whoever wishes to do it, they should consider it seriously, and do it. Yeah, it would be exciting.”
Mr Hossein – a criminal barrister – is up against London Assembly member Susan Hall, and former Downing Street aide turned tech entrepreneur Daniel Korski.