London could make history as the first major Western city to elect a Muslim mayor, with Labour Party candidate Sadiq Khan on top of opinion polls, according to NBC News.
Khan, the son of a bus driver from Pakistan, became a human rights attorney before entering politics, and supports gay marriage. His opposition, Zac Goldsmith of the Conservative Party, is the son of a Jewish billionaire and was elected to the House of Commons in 2010.
Goldsmith has criticized Khan for appearances alongside radical Muslim speakers and Khan has accused Goldsmith of running a "nasty, dog-whistling campaign."
The tense election is being likened to the 2016 presidential election, which has drawn global attention for the fighting and inflammatory remarks among candidates, namely from presumptive Republican Party nominee Donald Trump.
"The campaign has degenerated in a profoundly depressing way," London reporter and blogger for The Guardian, Dave Hill, told NBC News.