Polls open in Britain's election, as voters look set to punish big parties, reward upstarts

Labour Party leader Ed Miliband and his wife Justine leave the polling station after voting at Sutton Village Hall, Doncaster, England, Thursday May 7, 2015. Polls have opened in Britain's national election, a contest that is expected to produce an ambiguous result, a period of frantic political horse-trading and a bout of national soul-searching. (AP Photo/Jon Super) (The Associated Press)

Labour Party leader Ed Miliband and his wife Justine arrive at the polling station before voting at Sutton Village Hall, Doncaster, England, Thursday May 7, 2015, as Britain takes to the polls in a General Election. (AP Photo/Jon Super) (The Associated Press)

Polls have opened in Britain's national election, a contest that is expected to produce an ambiguous result, a period of frantic political horse-trading and a bout of national soul-searching.

Prime Minister David Cameron's Conservatives and Ed Miliband's Labour Party are running neck-and-neck, and neither looks able to win a majority of Parliament's 650 seats.

Many voters are turning elsewhere — chiefly to the separatist Scottish National Party, which will dominate north of the border, and the anti-immigrant U.K. Independence Party. UKIP is third in opinion polls but Britain's electoral system means it can win at most a handful of seats.

If no party wins outright, it may take days or weeks of negotiation to forge a workable government.

Polls are open Thursday from 7 a.m. (0600GMT) until 10 p.m. (2100GMT).