Who are the main players in the UK's upcoming national election?

Millions of voters in Britain are going to the polls Thursday to choose a new House of Commons and a new government. Voters will elect 650 lawmakers representing as many constituencies, or local areas, and the leader of the party that returns the most lawmakers will become prime minister. Prime Minister Rishi Sunak’s Conservatives are widely expected to lose to the main opposition party, the left-of-center Labour, after 14 years in power. The Conservatives and Labour traditionally dominate British politics under the U.K.’s “first past the post” electoral system, which makes it difficult for smaller parties to win representation in Parliament. But also in the running are the Liberal Democrats, Reform UK, the Scottish National Party and the Greens, among others.