Andy Burnham has given his full support to Sir Sadiq Khan seeking a fourth term as Mayor of London.
In an exclusive interview with The Standard, the Prime Minister also hit back at Tory mayoral hopeful Sir James Cleverly after he accused him of being “anti-London”.
Sir Sadiq has signalled that he will decide next year whether to call it a day after three terms in City Hall or seek re-election in 2028.
Former Greater Manchester Mayor Mr Burnham stressed that Sir Sadiq had done a “brilliant” job as mayor, including over his controversial Ulez ultra low emission zone.
He told The Standard: “If you look at the leadership on clean air, that is something that Sadiq deserves great credit for.
“Sometimes politicians take difficult decisions; they don't always get applauded at the time.
“But when that improves the health of millions of Londoners, then you've got to say one politician to another - that is leadership. I respect it.”
The PM added: “But he's done so much more as well. I could reel it all off.
“Sadiq is a really exceptional politician, a real leader, and absolutely, I'd love him to stay here as long as he wants, and I would certainly be behind him.”
Sir Sadiq would comfortably win a fourth term, according to the most recent Savanta poll for the Mile End Institute, Queen Mary University of London.
However, speculation has grown that he will not do so after he was made a peer by Sir Keir Starmer.
If he decides not to stand, possible Labour candidates include Brent East MP Dawn Butler, former Foreign Secretary David Lammy, MP for Tottenham, and Tooting MP Dr Rosena Allin-Khan.
In a further sign that Sir Sadiq may settle for three terms in City Hall, Ms Butler has already got the backing of the giant GMB union for a mayoral bid.
Former Home Secretary Sir James quit the shadow Cabinet to seek the Tory nomination for the mayoral contest.
The Braintree MP and ex-London Assembly member launched stinging criticism of Mr Burnham, accusing him of being “anti-London”.
Mr Burnham plans to move thousands, if not tens of thousands, of Whitehall jobs to the regions as part of his biggest ‘devolution of power in modern times”.
He has also signalled that he may raise tax in coming years on higher end homes, many of which are in London.
But the PM rejected the “anti-London” allegation from Sir James, branding it “ludicrous”.
He added: “I love London, and I have no hesitation in saying that.”
Highlighting a recent announcement in the Social and Affordable Homes Programme, he stressed: “You will see that London was the significant beneficiary.
“And the reason for that is because London has got more advanced housing powers.
“It's been able, with its 30 or so boroughs, to develop stronger plans to build a new generation of council housing in London.
“What we've done is we've set up London now with the funding to do that to be a template then for other parts of the country, so that they can follow the same path and then move in the same direction.”