Election 2015: SNP power could be limited after election

Professor John Curtice, of Strathclyde University said the anti Tory statements from the SNP leaves little bargaining power for the SNP if Labour forms a minority government.

Professor Curtice gave a lecture at Glasgow University on the current polls and what the political landscape could be after May 7.

He said the polls showed the SNP on course for a historic victory in Scotland and could be the third largest party in the UK if the Lib Dem vote collapses.

However he cautioned against such expectations.

He said: " Predictions of unprecedented success often tend not to be fully realised." And said he was talking both about the SNP and LibDems.

He said if there was a majority of Labour and SNP MPs then Mr Cameron would be gone as Prime Minister as he wouldn't get a Queen's Speech through Parliament.

But how much power the SNP could then influence on Labour remained to be seen.

He said: "The SNP only have leverage if they vote with the Tories"

He said the Fixed Term Parliament Act meant only a vote of no confidence defeat and two thirds of Parliament voting to dissolve parliament could trigger another election, meaning the SNP and Tories would need to unite.

He added that a Labour and Tory vote in favour of Trident would make it difficult for the SNP to scrap the weapons system renewal.

Professor Curtice said that the threat from Ukip in Tory seats was what was prompting the Conservatives to heighten fears over the SNP and Labour working together.

He said the Tories were "pushing the Scotland button" in order to attract voters who has defected to Nigel Farage's party.

Professor Curtice said that research shows that of the voters who though a Labour SNP alliance was a very bad thing, half, around 8%, were not supporting the Tories and half of them were Tories who jumped to Ukip

He said if the Tories could get 4% of Ukip voters back David Cameron could remain as Prime Minister.

He said that two thirds of lost Tory votes have gone to Ukip.