Britons have voted in local and regional elections that will choose a new mayor for London - and are expected to deal a blow to Britain's main opposition Labour Party.
Voters are electing a Scottish Parliament and legislatures in Wales and Northern Ireland, as well as choosing members of many English local authorities, including a new London mayor to replace flamboyant Conservative Boris Johnson.
The mayoral race pits the Labour Party's Sadiq Khan against Conservative Zac Goldsmith. Pollsters and bookies make Khan the favourite to win and become the city's first Muslim mayor, after a bitter campaign that saw Goldsmith accuse his rival of sharing platforms with Islamic extremists.
Khan, a former human rights lawyer and the son of a bus driver from Pakistan, accused wealthy environmentalist Goldsmith of trying to divide voters in one of the world's most multicultural cities, home to 8.6 million people - more than 1 million of them Muslims.
Tony Travers, a local government expert at the London School of Economics, said the introduction of a directly elected London mayor 16 years ago has "brought into politics an American form of government" that differs from traditional British Parliamentary and local government structures.
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"Now intriguingly this time - and we've seen a bit of it before - it appears to have brought with it some of the harder American campaign tactics," he said.
A victory for Khan would be a bright spot in what looks set to be a grim day for Labour, which has been out of office nationally since 2010.
Opposition parties usually gain seats in mid-term elections as voters punish the sitting government. But Labour under left-wing leader Jeremy Corbyn is divided and beset by a controversy over allegations of anti-Semitism within its ranks.
The furore erupted when former London mayor Ken Livingstone - a Corbyn ally - claimed that Adolf Hitler had supported Zionism before he came to power.
Livingstone, Labour MP Naz Shah and several local party officials have been suspended over comments or social media posts about Israel, and Corbyn has faced renewed pressure over his links to pro-Palestinian groups.
Corbyn predicted last week that Labour would not lose seats, but later said that "predictions are not that important."
A poor showing would bolster discontented Labour MPs who believe the party is heading for a third straight general election defeat in 2020 if Corbyn - a rumpled life-long socialist with strong support among the party's grass roots - is not replaced.
