Prime Minister David Cameron said he and Boris Johnson have discussed a possible return to Parliament for the London Mayor, but stressed a decision has yet to be taken.
Asked how likely a return was, Mr Cameron told BBC Radio 4's Today programme, "That's up to Boris."
He continued: "I've had this conversation with Boris and my message to him is 'You're a brilliant Mayor of London, you've done a great job, you've got a lot more to give to public life, and it would be great to have you back in the House of Commons at some stage, contributing to public life'.
"But that's up to him, but I'll certainly be giving him a warm welcome."
More top news
A Malaysian court has found a man guilty of murdering two British medical students in Borneo.
A Liberal Democrat parliamentary candidate has said he deliberately caught HIV after years battling depression.
Noel Edmonds beat off competition from Ant and Dec to be voted Britain's favourite children's TV presenter.