Nigel Farage’s Brexit Party has opened up a five-point lead in the polls ahead of next months European elections.
A YouGov poll, commissioned by the People’s Vote campaign, puts the Brexit Party on 27%, ahead of Labour on 22% with the Conservatives trailing on 15%.
The survey put the Lib Dems on 9%, the Greens on 10% and Ukip on 7%.
Change UK, the party formed from The Independent Group of ex-Tory and ex-Labour MPs, was trailing on just 6%.
It came as Vince Cable said the pro-Remain parties would have been better “fighting together under the same banner” in the elections on May 23.
Farage officially launched his new party last week and announced Annunziata Rees-Mogg – the sister of Jacob Rees-Mogg - as one of its MEP candidates.
But according to the survey, Labour would cut the Brexit Party’s lead to just three points if Jeremy Corbyn pledged to hold a second referendum.
The poll showed that in those circumstances, support for Labour would increase slightly to 23%, while support for the Brexit Party dropped to 26%.
Labour MP Margaret Beckett, a supporter of People’s Vote, said the poll showed if anyone can stop Farage winning it was Labour.
“There is nothing to be gained by denying that we support the public getting the final say which is what the overwhelming majority of our voters, members and MPs want,” she said.
“If we hedge our bets or say we back another form of Brexit, Labour loses voters and Farage will storm to first place.”
Theresa May has said she is determined to get a Brexit deal through parliament before that date, which would mean voting would be cancelled.
However, that not only means winning a “meaningful vote” on a deal – which has already been rejected three times by the Commons – but also then passing a bill formally ratifying the agreement in law.
Much is likely to depend on whether cross-party talks with Labour can agree a common way forward – with the two sides expected to take stock of progress when MPs return to Westminster after the Easter recess.