Londoners will elect a new mayor on Thursday in a race that pits the son of a billionaire against the son of a bus driver and presents an electoral test for the Conservative Party ahead of a referendum on whether the U.K. should leave the European Union. A loss for the Conservative candidate, Zac Goldsmith, would be a setback for the party of Prime Minister David Cameron. But it could also help Mr. Cameron in his campaign to keep Britain in the EU, less than two months before the June 23 referendum: Mr. Goldsmith, one of the U.K.’s richest politicians, backs a British exit from the bloc and says it would benefit London.
Sadiq Khan, the Labour candidate, who polls suggest is the favorite, sides with Mr. Cameron’s view that leaving the EU could threaten London’s economy. A survey by pollster YouGov PLC in late April put Mr. Khan 16 points ahead of Mr. Goldsmith, excluding those who don’t know or wouldn’t vote.
The post of London mayor has been held since 2008 by Boris Johnson, a prominent Conservative who is campaigning to leave the EU and who has clashed with Mr. Cameron in the increasingly heated debate. He isn’t running for a third term.