U.K. election: It's Theresa May vs. Jeremy Corbyn as Britons go to the polls

Britons went to the polls Thursday in a election expected to return Conservative Prime Minister Theresa May to power, although a late surge in the polls in favor of Jeremy Corbyn, the leader of the opposition Labour Party, indicated a President Trump-like upset was possible.

Six hundred and fifty parliamentary seats are up for grabs in the House of Commons. About 47 million people have registered to vote. Exit polls are expected shortly after voting finishes at 10 p.m. local time (5 p.m. ET), with the full results due sometime early Friday. A majority of 326 seats is needed to form a government.

May called the election, Britain's third national vote in two years, because she wanted to strengthen her party's majority as she heads into difficult talks with the European Union over the nation's impending withdrawal from the 28-nation political bloc. At the last election, in 2015, then-Conservative Prime Minister David Cameron won by a majority of 12 seats. Britain's referendum on EU membership in June last year was only narrowly approved by the public by by 52% to 48%.

May has vowed to build a "stronger, fairer and more prosperous Britain," while Corbyn's signature campaign slogan has been to govern "for the many, not the few."

A victory for May would leave Washington with a British leader prepared to work with President Trump despite clear differences over how to approach climate change, NATO and other global concerns. If Corbyn wins, Trump can expect a more adversarial partner who would likely openly challenge his positions.

But expectations that May would simply romp to victory over Corbyn have been undone amid recent terrorist attacks in Manchester and London as well as a lackluster campaign from May's Conservatives, who Richard Whitman, a professor of politics at the University of Kent, said have failed to connect with voters over key topics.

"The Conservatives believed that by simply making this vote about perceptions around May's strong leadership on leaving the EU this would win it for them. What they've found instead is that the electorate really is interested in detail on health care, education and social care issues."