When Jeremy Corbyn won the Labour Party’s leadership last September, party stalwarts in London also voted to choose a candidate to contest London’s mayoral election, one of many regional elections taking place on May 5.

Corbyn’s elevation marked the moment when Labour’s rank-and-file members ripped down the curtain on New Labour, ending the party’s two-decade move to the center that kept it in power for three consecutive terms under Tony Blair and Gordon Brown.

But it was perhaps the internal contest to lead Labour into London’s mayoral contest that struck the most damning blow.

The initial frontrunner, Tessa Jowell, pushed London’s bid for the 2012 Summer Olympics as a minister in the Blair government. When London, in fact, won the Olympics, she became the government’s minister for the Olympics as well. Jowell, a ‘Blairite’ long associated with the centrist incrementalism of New Labour, seemed like the perfect fit for one of the world’s financial capitals.

Instead, Labour voters turned to Sadiq Khan, a 45-year-old rising star of Labour’s ‘soft left’ flank. The son of Pakistani immigrants (his mother was a seamstress, his father a bus driver), it’s hard to conceive of a sharper contrast against his opponent, Conservative candidate Zac Goldsmith, the son of a billionaire.

Goldsmith’s father, James Goldsmith, won notoriety in the 1990s for his ‘Referendum Party,’ a eurosceptic forerunner of the United Kingdom Independence Party (UKIP). His son, just 41 years old, wasn’t an implausible candidate for London’s Tories. Like Cameron, Goldsmith is a moderate on social issues, and he is a former writer who spent nearly a decade as the editor of The Ecologist. But he has struggled to contest the image of a wealthy plutocrat out of touch with struggles of everyday Londoners. In April, he struggled to answer several ‘pop quiz’ questions in an interview about the city.

Moreover, Goldsmith’s campaign has been tainted by what even some Conservative critics have called Islamaphobic scare tactics. Those attacks have made Goldsmith seem not only demagogic but also desperate.

If polls are correct, Khan will easily defeat Goldsmith on Thursday.

That would make Khan the first Muslim mayor of a major western city, one of the world’s most powerful Muslim politicians and a potential Labour leadership contender. It will also give Khan the second-largest personal mandate of any political figure in Europe (after the French president) from a metropolitan population of 8.5 million. To keep perspective, that’s roughly the same number of people who live in all of Austria, and London’s population alone exceeds that of 13 EU member-states.

Khan, a civil liberties attorney, was first elected to the House of Commons in 2005 as an MP for Tooting in south London, the neighborhood where he was born and in which he grew up. Khan served briefly in the Brown government as minister of state for communities before a promotion in 2009 to transport secretary. After Labour’s 2010 electoral drubbing, Khan led Ed Miliband’s successful campaign for the Labour leadership, and he served as shadow justice secretary throughout Miliband’s time as leader, adding the London portfolio in 2013 to his shadow ministerial duties. Despite an unexpectedly difficult loss in the 2015 general election, Khan could point to London as one of Labour’s rare successes — the party gained seven seats there while hemorrhaging seats elsewhere in England. Though Khan is certainly no third-way Blairite, neither is he a hardline leftist in the mould of Corbyn or former mayor Ken Livingstone. In last summer’s leadership contest, for example, he backed Andy Burnham.

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Khan’s socioeconomic background alone makes him a unique figure in British politics. The fact that he’s of Pakistani descent and a practicing Muslim is even more amazing. If, as expected, he wins on Thursday, he will become not just a mayor but a symbol. At a time when a handful of disaffected second-generation or even third-generation Muslim youths, languishing in poverty in forgotten European suburbs, can find hope in radical jihadist Islam, Khan’s election will showcase that there are paths to success for immigrants and Europe’s growing Muslim population.

Though polls last year gave Labour a slight edge in the mayoral race, it wasn’t a foregone conclusion. So the decision to nominate Khan instead of Jowell wasn’t entirely without risk. Instead, those fears seem to be unfounded. Over the last eight months, polls show that Khan has expanded his lead over Goldsmith — a YouGov poll from mid-April gave Khan a lead of 48% to 32%, and a second-round advantage of 40% to 60%.

If Khan wins the instant runoff with more than 57.9% of the vote, he’ll become London’s new mayor with the largest mandate in the brief history of London’s elected mayors. Though the position comes with a high profile, the mayor’s office isn’t incredibly powerful — the national government in Westminster has far more responsibility. The current government has cautiously started to devolve more powers to London, including more direct involvement in the National Health Service. Blair’s government in 1998, alongside devolution to Scotland, Wales and Northern Ireland, created the Greater London Authority, including an elected mayor and a 25-member London Assembly.

In the last two decades, London’s voters have elected two idiosyncratic characters as mayor.

The first was Livingstone — ‘Red Ken’ to London’s tabloids — a Labour renegade closer to Corbyn ideologically than Blair/Brown and who vociferously opposed the war in Iraq. Livingstone was no stranger to controversy. He welcomed Venezuela’s late socialist president Hugo Chávez  to London with open arms, routinely criticized Israel’s treatment of Palestinians and was widely censured after making controversial anti-Semitic statements in 2006 comparing a reporter to a ‘concentration camp guard.’

Livingstone, however, ably supported the 2012 Olympics bid and won praise for shepherding the city through the aftermath of the July 7, 2005 bombings that killed 52 people. Nevertheless, he was suspended from the party just last week after making fresh anti-Semitic remarks, condemned both by Khan and Corbyn.

The second is outgoing mayor Boris Johnson, who twice defeated Livingstone, presided over the 2012 Olympics, now leads the campaign for the United Kingdom to leave the European Union and hopes to win the Tory leadership when prime minister David Cameron steps down.

Goldsmith, too, supports Brexit, an odd position for someone who wants to lead a city that could suffer greatly from Brexit. In contrast, Khan, like Cameron, chancellor George Osborne, much of the Conservative cabinet and much of the Labour Party, supports remaining a part of the European Union. That’s made it easier for him to win over supporters in the business community, who fear the adverse trade and other consequences of Brexit.

Khan has also tried to woo less wealthy Londoners, many of whom feel crushed by the city’s global attraction — and the exorbitant cost of living that has resulted. At the center of Khan’s campaign is a pledge to freeze prices for public transportation, including the Tube, London’s subway system. Both candidates agree that London needs much more affordable housing, and Khan has explicitly targeted a goal for 50% of all new housing to be deemed affordable. Neither candidate supports the long-discussed expansion of Heathrow, London’s main international hub, but Khan supports expanding Gatwick, just south of London.