A victory by Khan would be a signal moment in both British and European politics, to say the least. One year after Labour’s thorough defeat in the general elections, retaking London City Hall would a much-needed boost for the party as it tacks to the left under Jeremy Corbyn, its leader. It would also usher in the first Muslim mayor of the European Union’s largest city, a historic milestone as the continent, much like Britain itself, wrestles with identity, immigration, and integration.

Khan, for his part, does not see his identity as a British Muslim in binary terms. “I’m a Londoner, I’m European, I’m British, I’m English, I’m of Islamic faith, of Asian origin, of Pakistani heritage, a dad, a husband,” he said in a New York Times interview. In the campaign, he’s emphasized core issues for Londoners such as affordable housing and transportation. But his overall message is one of cosmopolitanism and embracing London’s diversity.

Zac Goldsmith, the Conservative candidate and Khan’s principal opponent, has a different origin story. A wealthy scion of a billionaire banker and the British aristocracy, the 41-year-old Goldsmith seemed like a natural leader in the next generation of Tories. He set himself apart through his interests in direct democracy and environmentalism, the latter of which was nurtured by years writing for an ecology-oriented magazine.

But as the campaign entered its final weeks, the clash turned to issues of religion and ethnicity. In April, Goldsmith accused Khan of “giving platform, oxygen, and cover” to Muslim extremists, which Khan vehemently denied. British Prime Minister David Cameron then echoed his Conservative colleague’s remarks on the House of Commons floor and criticized Khan for appearances alongside Sulaiman Ghani, a fundamentalist imam in Tooting, the constituency Khan represents in Parliament.

“Suleiman Gani—the honorable member for Tooting has appeared on a platform with him nine times. This man supports [ISIS],” he said to jeers and cries of “racist!” from Labour MPs. “They are shouting down this point because they don’t want to hear the truth.”

Cameron’s comments unleashed a barrage of criticism from Labour, who accused the prime minister of Islamophobia and dog-whistle politics. “The PM thinks it is a crime for Sadiq Khan to be a Muslim and have been a human rights lawyer,” tweeted Chuka Ummah, a prominent Labour MP. “I think this Donald Trump approach to politics, trying to divide communities, turn them against each other—I don’t think that will work in London,” Khan told reporters in response to the controversy.

Ghani, for his part, denied any support for ISIS. News reports subsequently emerged that Goldsmith too had once been photographed alongside Ghani, and that a Conservative MP candidate had sought the imam’s help in recruiting Muslim Tories during the last election.