As a fellow politician, I used to like and respect Zac Goldsmith. After his mayoral campaign, I don’t any more

Goldsmith has disgraced himself and the Tories. Even people in his own party are now urging people to vote against him

Zac Goldsmith is the Conservatives' mayoral candidate for the London elections (Getty Images)

When I entered Parliament in 2010 I must confess that I approached it with a tribal attitude, especially when it came to MPs from other political parties. I was soon disarmed and found that there are reasonable and talented politicians on all sides of the House. One of these was Zac Goldsmith.

I was always impressed by Zac’s independence, his commitment to his constituents and his willingness to stand up to the Prime Minister from his own party. He was a rising star. That star has now fallen.

When Zac Goldsmith secured the nomination to be the Conservative Candidate for Mayor of London, I was hopeful that this would be a race between two highly energised, thought-provoking candidates. I anticipated their ideas would fizz off each other, creating a culture where the Punch and Judy politics of old was replaced with a more consensus based, cerebral approach underpinned with passion and pride.

I have been woefully disappointed in the campaign that Zac has run. It has been nothing short of disgraceful and he deserves all of the criticism that will inevitably come his way. Zac is guilty of pulling politics into the gutter.

Rather than responding to the positivity of Sadiq Khan’s campaign, Zac Goldsmith has decided to play the man, rather than the ball. The problem with this approach is that Sadiq has been a tireless campaigner for London, and the accusations levelled at him from the Tory camp are out and out lies, designed to smear Sadiq’s reputation.

Zac’s campaign has sunk to the low of dog-whistle politics, trying repeatedly to link his faith with extremism. The sort of nudge-nudge wink-wink politics we thought we left behind in the 70s and 80s. So bad is it that even those on his own side are lining up to denounce him.

Peter Oborne, that well-known socialist, is so disgusted with Zac’s campaign that as a committed Tory, he feels he cannot vote for him and will be voting for Sadiq instead, calling on all decent Tories to do the same. Sayeeda Warsi has criticised the way in which the Tories have wanted to win by trashing Sadiq’s reputation as opposed to winning the argument.

What Oborne said was right. If we cannot vote for a Muslim in Sadiq Khan, which Muslim can we vote for? Sadiq has been at the forefront of human rights campaigns, fronting the well-respected organisation Liberty. He voted for equal marriage, something which many Tories could not bring themselves to do. He has been a tireless campaigner against extremism. If this is not someone who we can vote for, then I am dumbfounded.

London is a city made up of many communities, and Sadiq Khan recognises that. I believe him when he says that he will be a Mayor for all Londoners, not just for some. In contrast, Zac Goldsmith has tried to divide Londoners, sending out racially profiled leaflets aimed at stirring up doubt and suspicion.

Zac Goldsmith’s divisive and dangerous campaign is not reminiscent of the decent man that I have known for the last six years. In setting out to smear and slur Sadiq, he has shown how the Tories have truly turned into the nasty party once more. It seems that Zac is taking the advice of his aides rather than running a campaign that reflects his personality.

It is heartening to see how Sadiq has risen above the attacks, taking the polls with him. This kind of divisive, dog-whistle politics does not work in London.

Karl Turner is the Shadow Attorney General, MP for Hull East