THE war between the Westminster and Scottish Conservatives over the Downing Street “partygate” scandal risks leading to sliding support for the party and the Union, according to a polling expert.

Mark Diffley, founder and director of the Diffley Partnership, said the fate of Boris Johnson was getting more precarious with the continuing revelations about social events during lockdown.

But he said the longer the Prime Minster stays around, the more likely it is the polls will go in the wrong direction for the Tories – which is likely to impact on how “secure” the Union is.

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Scottish Tory leader Douglas Ross called for the Prime Minister to go on Wednesday, which led to a backlash from senior Tories south of the border. Leader of the House of Commons Jacob Rees-Mogg called the Scottish Conservative leader “quite a lightweight figure”.

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The Tory group at Holyrood has largely supported Ross, with one saying Rees-Mogg should “have a long lie down”.

Diffley said Ross was likely to be looking at polls both north and south of the border which show increasingly the Prime Minister is a “drag on Conservative support”.

He also pointed to the most recent independence polls which have recently shown the Yes side edging ahead.

“If Johnson survives this, there is going to be a significantly poor relationship between the two parties,” he said.

“There is every anticipation intuitively the polling numbers will continue to slide away, as far as support for the Tories, support for Johnson and support for the Union are concerned.

“That is the risk. If he doesn’t survive, I suppose there is the opportunity to rebuild a relationship with whoever takes over.”

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Margaret Thatcher’s former Scottish secretary Malcolm Rifkind has said he believes the spat has “no impact whatsoever” on the future of the United Kingdom.

However, Diffley said: “The longer [Johnson] stays around, the more difficult this is clearly going to be for Douglas Ross and for the party here.

“There will be no relationship really to speak of, the polls will just go in the wrong direction and that is likely to probably impact on how secure the Union is.

“Of course, if you are in the Yes camp, you must be thinking this could be the moment to try and push this.

“There could be some movement as far as ramping up the case for a second referendum is concerned, I wouldn’t be surprised if that is the case.”

Diffley said the idea of the Scottish Tories forming some kind of breakaway party did not come without risk, pointing to examples such as the Alba Party and Change UK.

“All these parties which were formed try and shake things up on various issues – they tend to really not succeed,” he said.

“Embarking on that three or four months ahead of the local elections would be a really, really difficult thing to do.”

Politics expert Dr Alex Smith, of Warwick University’s department of sociology, who has written a book on devolution and the Scottish Conservatives, said Ross’s call for Johnson’s resignation was motivated by concerns about the impact on the Union.

“The kind of Unionists who are not keen on the Tories, they are the ones who if you are really passionate about Unionism in Scotland you would be worried about,” he said.

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“They are the ones who might start to think about the price of being in the Union or supporting the Union, being that we have to put up with this nonsense.

“To the credit of the Scottish Tories, they are probably thinking of their commitment to the Union as being more important than their commitment to the party, as any kind of internal criticism of a leader in party will go down badly.”

He added: “It does affect the Scottish Tory brand, but I think the thing they are more worried about is how it affects the Unionist brand.

“The best thing for Nicola Sturgeon is if Boris Johnson survives this scandal and it just rumbles on and on and on.”