A push toward Brexit could trigger the SNP to push for a second Scottish independence referendum.
The suggestion was made by SNP leader Nicola Sturgeon during the Scottish leaders' debate on Wednesday. Challenged over whether her party would push for a second independence referendum, Sturgeon said the SNP was not "planning or proposing another referendum".
But she added a caveat that could prove fundamental to the future of Scottish politics. "Something material would have to change in terms of the circumstances, " she said. "Perhaps if the Tories wanted to drag us out of the European Union against our will."
David Cameron has promised that if the Tories win the General Election Britain will renegotiate its terms of membership of the EU and put the new deal to a referendum. However, the Prime Minister has made clear that he wants Britain to remain in the EU.
The SNP is a fervently pro-EU party and at one point wanted an independent Scotland to join the euro. In the past Sturgeon has questioned the legitimacy of a future EU referendum result where the UK as a whole voted for Brexit but the majority of Scots voted to stay in.
Last year, Scotland voted decisively to remain in the UK by a margin of 10 points. But since the referendum the SNP has enjoyed a surge in membership and is riding high in the polls.
The latest YouGov poll put SNP support at an all-time high on 49 per cent while Labour's rating dropped to an all-time low of 25 per cent. If the YouGov poll was reflected on polling day, Labour would be reduced to just four seats in Scotland.