George Osborne has dismissed allegations Zac Goldsmith ran an Islamophobic campaign against Sadiq Khan in the contest for London mayor.
The chancellor said the contest had simply been a bit of "rough and tumble" that comes with democracy and elections.
Khan, who handily won the mayoral election last week, this morning accused the Conservatives of running a "nasty" campaign that was "straight out of the Donald Trump playbook".
Several Conservatives have also accused Goldsmith of targeting Khan's Muslim faith during the election.
Speaking to ITV's Peston on Sunday programme, Osborne rejected the idea Goldsmith had run a racist campaign.
"All the questions we were asking are the questions we're asking of Jeremy Corbyn: who do you associate with, where do you come from, what are your thoughts and ideas?," he said. "And these are perfectly legitimate questions to ask."
But the chancellor acknowledged the Tory strategy against Khan had not worked. "I’ve been on winning general election teams and losing general election teams and when you lose a campaign, in the days afterwards, every single thing you did was wrong," he said.
"I went campaigning with Zac, when I was with him he was arguing for more infrastructure in London, we were talking to young tech entrepreneurs in London, there was a positive campaign there but obviously it didn’t work in the end.
He added: "Of course Zac has a future. He’s a brilliant member of parliament for Richmond, he’s got incredibly important ideas about the environment, he’s independent minded, he will be on the Tory benches making his views pretty clear."
Labour's former deputy leader, Harriet Harman, was not impressed.
Andrew Boff, the former leader of the London Assembly’s Conservative group, has said that he and many other Tories in the capital were “really troubled” by the Goldsmith tactic of painting Labour’s candidate as an extremist.
After the polls closed on Thursday, Boff told Newsnight that he had told his colleague that it was “a mistake” to attack Khan with such allegations as it undermined the party’s hard work in appealing to the Muslim community.
“I don’t think it was dog whistle, because you can’t hear a dog whistle. Everybody could hear this,” he said.
Furious Labour MPs have claimed that it was “racist” to suggest that Khan’s Muslim faith was a danger to Londoners.