Britain's Labour Party will only back an early election if an extension long enough to allow for a snap poll is agreed with the European Union and a no-deal Brexit is off the table, a source in the opposition party said on Tuesday. Labour has long said it wants a new election, but has so far refused to support Prime Minister Boris Johnson's calls for one because the opposition party fears he might lead Britain out of the EU without a deal. The source, speaking on condition of anonymity, said there would need to be an extension long enough to hold a new election for the prime minister to get Labour's support for a snap poll.