A Scottish Tory grandee has said Ruth Davidson should back a second referendum on Brexit if she wants to replace Nicola Sturgeon as First Minister.

Struan Stevenson, who was a Conservative MEP for 15 years, said the failure to strike a Brexit deal is harming Davidson, adding that support for a confirmatory would help her make up “lost ground”.

Davidson made her return to front-line politics this month at her party conference in Aberdeen after six months on maternity leave.

One of the main themes of the party gathering was promoting the Scottish Tories as an alternative party of Government in 2021, which would result in Davidson becoming First Minister.

However, Davidson’s allies fear that the stalemate at Westminster over the failure to strike a deal to leave the European Union is damaging the Scottish party.

Although Davidson campaigned for Remain in the 2016 referendum, she accepted the result and has supported Prime Minister Theresa May’s draft withdrawal agreement.

Opinion polls have consistently shown that the Tories on both sides of the border are losing support to Nigel Farage’s Brexit Party ahead of this week’s European elections.

The UK party, according to a recent poll, is on less than 10%, while the Scottish Tories fear losing their only European seat.

Stevenson, 71, who was a Tory MEP between 1999 and 2014, said the Scottish party’s prospects are “not looking great” ahead of Thursday’s election.

He said hundreds of thousands of pro-Remain Tories, such as himself, are effectively politically homeless.

Speaking to this newspaper, he said: “The majority up here who voted Remain are now looking for a home for their votes. Ruth Davidson’s leaflet came out today saying ‘we want no more referendums’.”

He added: “Where do people like me, strong Remainers, go?”

The Scottish Tories are opposed to a second Brexit referendum – many in the party believe it creates a precedent for indyref2 – but Stevenson believes this stance is wrong:

“What we should have said is that any deal that is struck must be subject to a ratification referendum.

“As Conservatives, we are intrinsically against breaking up any Union. That is not only the Union of the UK, but also the European Union.”

“We are a Conservative and Unionist party. And this is the European Union. I don’t see any anomaly in saying we are against leaving the EU and we are against breaking up the UK.”

He said he fully supports Davidson’s bid to become First Minister but, asked whether he is worried that the Brexit crisis is jeopardising her chances, he said:

“I am. Ruth has done a fantastic job. She was riding on the crest of a wave when she went on maternity leave. During her six months on maternity leave, things went into meltdown in England. The party is in open mutiny against the Prime Minister now, and it is all because of Brexit.”

Stevenson said a pro-referendum position would be an “attractive proposition” for Davidson because it would open her up to Remain voters:

He added: “If they had agreed to back this, it would have made a difference [in the European election]. Sadly they haven’t agreed to back a confirmatory referendum.”

He urged a rethink after the election: “That would certainly be the best way to ensure Ruth Davidson makes up lost ground, ground that was lost because of what happened in England.”

Aileen McLeod, an SNP candidate in the European elections, said: “The Tories are fully signed up to a damaging Brexit that will destroy jobs and damage our NHS - that’s the bottom line. That's what Ruth Davidson's party stand for, however they might try and dress it up. Our message is crystal clear - a vote for the SNP next Thursday is a vote to stop Brexit.”

A spokesman for the Scottish Conservatives said: “We always welcome and respect Struan’s input into such matters. But our clear view is that Brexit has to be delivered quickly and efficiently so Scotland can move on from referendums once and for all.”