POLITICAL experts believe tactical voting will not have a significant impact in Scotland despite the rise of a pro-Union grassroots movement to reverse a massive upsurge in support for the SNP.

Senior academics claim the increase in support for the Nationalists in the General Election campaign is due in part to a post-referendum bounce and the party’s progress is unlikely to be challenged by Labour or Tory supporters switching to “an anti-Nationalist vote”.

The Scottish Tories yesterday sought to win support by presenting the campaign as another “fight for the Union” with the unveiling of the No camp’s “No thanks” referendum poster as part of its “new” publicity materials.

It also emerged yesterday that a number of campaign groups – including one calling itself Scotlandsbigvoice – have been established in a bid to get voters to support the strongest rival Unionist party, whether Labour or Conservative.

The group has sent leaflets, printed outside Scotland, to voters advising them how they can vote to “protect Scotland and maintain unity”.

SNP politicians have condemned the grass-roots groups as “a Tory front” pointing out that they are urging people to vote for the Conservatives in four seats that the Lib Dems hold and one which is held by Labour.

“The fact that tactical voting campaigners are actually urging a Tory vote in four seats that the Lib Dems currently hold and in one Labour seat shows that this is a pro-Tory front to try and get David Cameron back into government,” said Christian Allard, the SNP MSP.

“That is the last thing that people in Scotland want which is why the SNP has vowed that we will never do a deal to let the Tories back into office.

“Electing a strong team of SNP MPs will ensure David Cameron is locked out of Downing Street and will provide a strong voice for Scotland and help to encourage a new, better and more progressive politics at Westminster – for everyone.”

Professor John Curtice of Strathclyde University said there were only a handful of constituencies in Scotland with the ideal conditions needed for tactical voting to be possible due to the demise of the Tories and Liberal Democrats.

“The SNP is so far ahead, tactical voting is not going to have a significant impact. It may make a difference in the odd constituency but the problem as far as the Unionists are concerned is that there aren’t very many places where the ideal situation is clear for tactical voting.

“The ideal tactical voting constituency is one where the SNP and a Unionist party are both somewhere around 40% of the vote and where you have got a third party or parties gathering about 20% of the vote. Then if you can persuade not too large a number of the 20% to move to support the Unionist party that may make a difference to the outcome,” he said.

“The problem is that there’s hardly a Liberal Democrat left in Scotland, there are large parts of Scotland where they are heading for just 2% of the vote, so they are irrelevant. Also in terms of the Tories there are quite a lot of places in Scotland where they’re not going to get much more than 10% of the vote and in constituencies where the SNP is heading over 50% tactical voting is simply irrelevant.”

Curtice added that seats where tactical voting could make a difference included East Dunbartonshire, where the LibDem Jo Swinson faces a battle to keep her seat, Dumfries and Galloway where Labour’s Russell Brown is hoping to be re-elected, and Edinburgh West where LibDem Mike Crockart is also fighting to remain in the Commons.

But Professor Paul Cairney of Stirling University agreed the SNP surge was unlikely to be affected overall.

He said: “The ‘anyone-but-the-SNP’ tactical voting campaign is unlikely to work. It’s not coordinated and it’s hard for people to know which party to vote for to make sure they are voting correctly as they see it.

“The problem for tactical voters is that because the SNP have picked up so much support from other parties it’s not clear who in each seat is second in the running.”

A string of polls have predicted a SNP triumph at the polls next month with the party winning as many as 56 of the 59 seats in Scotland.