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 painting by artist LS Lowry is to go on show to the public for the first time.
A third of Olympic and world championships medals have been won by athletes with allegedly suspicious doping test results, report claims
Migrants trying to get to Britain made a mass attempt to break into entrance to the Channel Tunnel near Calais in France late Saturday.