LONDON — London is expected to become the first Western capital with a Muslim mayor this week despite an increasingly desperate and divisive Conservative campaign against him.

A former Conservative Party candidate for the House of Commons told The Daily Beast that Prime Minister David Cameron and his party were running “a purely racist campaign” against human-rights lawyer and prospective London mayor, Sadiq Khan.

“The Conservative Party are fighting Sadiq Khan for being a Muslim and not fighting him for being Labour,” said Shazia Awan. “What they are doing is fundamentally wrong.”

Awan, who has worked alongside Conservative leaders including Cameron, William Hague and Margaret Thatcher, said she was heartbroken to see the party stoop to racial division.

After Khan took a commanding lead in the opinion polls, Zac Goldsmith, the Conservative candidate, and his allies began to paint Khan as a “dangerous” radical with links to Islamic extremists.

When he was working as a lawyer Khan did represent a number of what he described as “unsavoury individuals” some of whom were convicted of terror-related offenses.

Goldsmith’s closing pitch to the electorate in the race to replace Boris Johnson was a controversial article in the Mail on Sunday in which he described the risks of handing over control of Scotland Yard and London’s counter-terror command to Khan.

The article appeared below an image of the wreckage of an iconic red London bus that was destroyed during the 7/7 attacks that killed 52 people in 2005.

Former Conservative party chairwoman Sayeeda Warsi was among those to express her horror at the use of the atrocity.

After more than 24 hours of silence, Goldsmith said it had been “inappropriate” for the newspaper to use the image, which remains prominent at the top of the online version of his op-ed.

Goldsmith and Cameron have repeatedly claimed that there are links between Khan and Islamic extremists, including the British imam Suliman Gani, with whom Khan has appeared at events in London.

Goldsmith, incidentally, also invited Gani to a campaign event and has posed for a photograph with him.

While speaking in the House of Commons, the prime minister attacked Khan for “sharing a platform” with Gani whom he said “supports IS [or ISIS].” The Daily Mirror has probed this claim and thrown substantial doubts on Downing Street’s supposed evidence.

Cameron then changed the wording of his attack to say Gani “wanted an Islamic state” when he repeated the accusations against Khan on Wednesday, the eve of polling day.

Cameron also attacked Labour a week after an MP and one of the party’s most senior advisers were suspended after a shameful public spat over anti-Semitism that ended with an argument between senior party members in the street.

Peter Oborne, one of Britain’s most formidable Conservative columnists, was appalled that Cameron used his high office in such a way, “enthusiastically playing the politics of religious division.”

“Like many other Tories, I welcomed [Goldsmith’s] emergence as Tory candidate for mayor of London and planned to vote for him,” Oborne wrote. “Wild horses could not make me do so now. Goldsmith’s campaign for mayor has become the most repulsive I have ever seen as a political reporter.”

Shazia Awan said she would be voting Labour for the first time in her life. “As a British Muslim myself I find it horrific and repulsive that they are labeling someone who is a human-rights lawyer as radical and dangerous,” she said. ”They are trying to tarnish this liberal, chilled-out Muslim guy as some kind of extremist.”

Awan spoke out against her own party for the first time on Monday in an article for the New Statesman, which Labour leader Jeremy Corbyn quoted to Cameron in Parliament on Wednesday.

Before going further and telling The Daily Beast that the campaign was “racist,” she highlighted the use of racial profiling for direct-mail hits that seemed designed to sow discord between London’s Hindu, Sikh, and Muslim populations.

Londoners with Guajarati names, for example, have complained that they received letters highlighting Cameron and Goldsmith’s respect for the Hindu Indian prime minister, Narendra Modi, while raising concern over the Muslim Khan’s ability to keep London safe.

Awan, an executive and PR consultant, said the Conservatives were “playing off London’s diverse communities against each other—playing off Guajarati Hindu communities and the Punjabi Sikh community against the Muslim community.”

The former parliamentary candidate for the district of Leigh said she had experienced plenty of overt racism while working at the grassroots level, but she said had always been protected by senior figures in the party who said she should ignore the views of belligerent old party members.

She said she had been inspired to try to become an MP by Cameron, who she insisted was not racist.

“But for David Cameron to repeat that grassroots rhetoric and take it to the House of Commons that gives it legitimacy,” she said, “that is disheartening.”