LONDON -- Brexit talks between Britain's Conservative government and the main opposition Labour Party resumed Monday with little sign of progress, as the two parties remained far apart on terms of the U.K.'s departure from the European Union.

Senior Conservative and Labour officials have been meeting for weeks in an attempt to find a compromise Brexit deal that can win majority support in Parliament.

Labour Brexit spokesman Keir Starmer told Monday's Guardian newspaper his party would only support a deal if was put to a referendum vote.

Starmer said that as many as 150 of Labour's 246 lawmakers "would not back a deal if it hasn't got a confirmatory vote."

Prime Minister Theresa May has rejected a new referendum, saying voters made their decision in 2016 when they narrowly opted to leave the EU.

Foreign Secretary Jeremy Hunt said it was "a crunch week" for the talks.

He said the Conservative Party believed a new referendum "would be a betrayal of what people voted for, and we want to implement the first referendum. But let's see where these talks go to."

If the cross-party talks fail, the government says it will give Parliament votes on a series of Brexit options in an attempt to see if any has majority support.

Previous "indicative votes" failed to find agreement on any way forward.

The U.K.'s departure from the EU, long set for March 29, has been delayed until Oct. 31 while Britain's politicians try to break the deadlock.

Anger at the Brexit morass is fueling support for smaller parties ahead of a European Parliament election next week. The newly formed Brexit Party, led by former U.K. Independence Party head Nigel Farage, is leading opinion polls for the May 23 contest and could take the largest share of Britain's 73 seats in the EU legislature.

The pro-EU Liberal Democrats have also seen their popularity surge as voters turn their frustration on the two big parties.

Conservative lawmaker Huw Merriman said his party faced "an absolute mauling" in the European election.

He told the BBC that pro-EU voters will "blame us for having tried to take us out" of the bloc.

"And for those that voted to leave, they'll blame us for having not got the country out of the EU," he said. "We're at the perfect storm."