Nicola Sturgeon is predicting an "almost certain" drive for another independence referendum if Scotland votes to stay in the European Union (EU) but England votes to leave.
This prospect will undoubtedly be at the back of voters' minds as they go to the polls to elect their next batch of MSPs next month, with the EU referendum looming just seven weeks later.
With all of Scotland's major parties firmly in the Remain camp, there has been little argument between them, leaving them free to focus on crucial issues of taxation and spending in Scotland.
Parties south of the border seem to have caught the referendum bug that infected Scotland in 2014 where Leave or Remain have become "proxies" for policies - principally immigration, national sovereignty and foreign affairs.
This has subsequently brought to the fore some of the powers Holyrood does not currently hold but which the nationalists say they would manage differently.
For nationalists a Brexit could represent the next big push towards independence, and for unionists it will be all the more reason to back a pro-UK party.
Ms Sturgeon has stressed she is not in favour of a Brexit under any circumstances - she wants an independent Scotland in the EU side-by-side with its closest neighbour.
This is despite polls showing a Brexit could push support for independence into a slight majority, but it is unclear how Scots would react once the realities sink in.
Even a swift post-Brexit IndyRef2 would take time to arrange, giving voters pause to adjust to the new political reality and weigh up the implications of foresaking a neighbouring union to assert your attachment to a more geographically distant one.
English reaction to a Brexit could be crucial in saving or breaking the union - particularly if it leads to a rise in English nationalism that is already being felt in the rising support for Ukip and the drive for English-votes-for-English-laws.
Christine O'Neill, chairman of Brodies, a specialist in constitutional law and former adviser to Holyrood's Devolution (Further Powers) Committee, said: "I think that many people would see the referendum on EU membership as being about a debate over relatively discrete policy issues - principally the UK's approach to inward migration from inside and outside the EU - more than a debate about broader questions about national identity, the internal market or the legitimacy of EU institutions".
Why are you making commenting on The Herald only available to subscribers?
It should have been a safe space for informed debate, somewhere for readers to discuss issues around the biggest stories of the day, but all too often the below the line comments on most websites have become bogged down by off-topic discussions and abuse.
heraldscotland.com is tackling this problem by allowing only subscribers to comment.
We are doing this to improve the experience for our loyal readers and we believe it will reduce the ability of trolls and troublemakers, who occasionally find their way onto our site, to abuse our journalists and readers. We also hope it will help the comments section fulfil its promise as a part of Scotland's conversation with itself.
We are lucky at The Herald. We are read by an informed, educated readership who can add their knowledge and insights to our stories.
That is invaluable.
We are making the subscriber-only change to support our valued readers, who tell us they don't want the site cluttered up with irrelevant comments, untruths and abuse.
In the past, the journalist’s job was to collect and distribute information to the audience. Technology means that readers can shape a discussion. We look forward to hearing from you on heraldscotland.com
Comments & Moderation
Readers’ comments: You are personally liable for the content of any comments you upload to this website, so please act responsibly. We do not pre-moderate or monitor readers’ comments appearing on our websites, but we do post-moderate in response to complaints we receive or otherwise when a potential problem comes to our attention. You can make a complaint by using the ‘report this post’ link . We may then apply our discretion under the user terms to amend or delete comments.
Post moderation is undertaken full-time 9am-6pm on weekdays, and on a part-time basis outwith those hours.
Read the rules here