The pro-remain Change UK party has suffered an embarrassing setback in Scotland after its lead candidate in the European elections urged voters to back the Liberal Democrats.

David Macdonald, an independent councillor in East Renfrewshire, said pro-remain voters who also opposed Scottish independence should back the Lib Dems in next week’s vote. He said he would stand down as Change UK’s top candidate.

Macdonald said he believed Change UK was splitting the remain vote, which would allow Nigel Farage’s Brexit party to win one of Scotland’s six European seats unless pro-UK remain voters rallied behind the Liberal Democrats.

“We have a much more diluted remain vote in Scotland and it’s becoming very clear and apparent close to these elections that we’re in grave danger of splitting this vote,” he said, standing alongside the Scottish Lib Dem leader, Willie Rennie.

“It’s very clear to me now that what needs to take place is we need to shore up the remain vote.”

He said it was “one of my greatest fears” that Farage’s party would win a Scottish seat. “Ultimately we want to stop that. We want to send a clear message from Scotland that we’re very much wanting to remain in the European Union.” he said.

Lib Dems and Change UK must stop bickering and unite for the Euro vote | Andrew Rawnsley Read more

Macdonald said he also wanted to shore up the pro-UK remain vote in Scotland, since only the Lib Dems and Change UK were both anti-Brexit and anti-Scottish independence. He said the SNP was sending voters “a very mixed message” by trying to attract remain voters while campaigning for independence.

Change UK, which has no elected representatives and is yet to have much impact in Scotland, is due to hold its first and only Scottish election rally in Edinburgh this weekend. Macdonald’s name will remain on the ballot paper for Change UK, since it is too late to remove it.

Chuka Umunna, Change UK’s spokesman, said the party was making headway in other parts of the UK and Macdonald’s decision was regrettable.

“He has let down his fellow candidates and activists,” Umunna said. “But we are focusing all our efforts on adding to the remain vote in the UK and challenging the pro-Brexit Tory, Brexit and Labour parties.”

The political landscape in Scotland is more crowded than in many other European parliamentary regions in the UK, with four parties fighting for the remain vote – the SNP, Scottish Greens, Lib Dems and Change UK.

There is an additional layer of complexity for pro-remain voters in that both the SNP and the Scottish Greens support Scottish independence and see Brexit as a clear justification for staging a second referendum on leaving the UK.

The latest opinion polls put the SNP on about 40% and on course to win three or four seats, with Labour expected to win one. There is a fierce battle for the two remaining seats, with the Brexit party competing neck and neck with the Tories for one of those places.

A YouGov opinion poll last month suggested the Lib Dems were tied with Change UK at 6%, meaning neither party had a chance of winning a seat. Rennie hopes Macdonald’s switch will boost the Lib Dems’ support and attract pro-remain Labour voters who are disillusioned with the pro-Brexit stance taken by Jeremy Corbyn.

A businessman who founded the TriBeCa restaurant chain, Macdonald had been out campaigning for Change UK in Stirling on Tuesday night. He insisted he respected the party and believed it had a significant role to play in British politics, but said he would not stand for it again.

The Scottish Lib Dems insist they still want to work with Change UK in future, but Macdonald’s switch suggests the Lib Dems are keen to assert themselves as the senior partner in any future partnership.