Change UK could form a pact with the Liberal Democrats to not stand against each other’s candidates in the next general election, the party’s spokesman has said.

Former Labour MP Chuka Umunna said politicians who want Britain to remain in the EU need to work “even more closely together” following the European elections.

His party’s leader, Heidi Allen, admitted she threatened to quit in an internal row over tactical voting to maximise the pro-remain challenge to Nigel Farage’s Brexit Party.

Mr Umunna told BBC Radio 4’s Today Programme on Saturday: “The remain forces in this country need to work even more closely together than we have managed to achieve up to this point between now and the general election.”

Asked if Change UK could form a pact with the Liberal Democrats – similar to the alliance between the SDP and the Liberal Party in the 1983 general election – where their candidates do not stand against each other, Mr Umunna said: “I think it would be sensible.”

He added: “I personally don’t think we should be competing at a general election and, of course, whilst we had a system of proportional representation at the European elections, it’s going to be first past the post in a general election, so we have got to get our ducks in a row and work out what configuration is appropriate for 2019 and beyond instead of just perhaps using the same model from the 1980s.”

Earlier this week, Ms Allen was asked if she had threatened to quit as Change UK leader over an internal dispute over whether to publicly back the Liberal Democrats outside London and the South East.

She told Channel 4 News: “Yes. I did. I am very, very troubled by this. This is a massive decision for a party to take. Had it been left to me, I would have absolutely advised tactical voting.”

Ms Allen, who left the Conservative Party to join other breakaway Tory and Labour MPs, said the majority view was that “they didn’t want to go that way”.

She added: “But it is something that still troubles me. I have no doubt that the British public will look at the tactical voting websites out there and make their own decisions.”