The SNP have seized on a growing rift between unionist parties over the role David Cameron might play in the anti-independence campaign ahead of a referendum.
With the momentum behind First Minister Alex Salmond there are concerns on the unionist side that the case against independence is not being made.
The difficulty facing the Tories and Labour is finding a figure big enough to take on the SNP, who are getting their message across almost unopposed.
The natural figure to lead the fight against the break-up of the United Kingdom would be the Prime Minister, but there are fears among pro-unionists that a high-profile role for Mr Cameron could backfire as he could be seen by Scots voters as an English outsider.
It has even been suggested Mr Cameron’s involvement would play into SNP hands in that he would be painted as depriving Scots their right to self-determination.
Within Labour the idea of Mr Cameron heading up the anti-independence campaign has caused dismay.
Prominent Scottish labour MP Ian Davidson said: ”Anyone who believes Cameron is the best person to lead the anti-separation forces has not much understanding of the politics of Scotland.”
Shadow defence secretary Jim Murphy has made it clear he would not share a platform with the Mr Cameron during the referendum campaign.
The new Scottish labour leader Johann Lamont has also let it be known she will not campaign alongside the Prime Minister.
Other Labour MPs take a different view Glasgow South’s Tom Harris and Dunfermline MP Thomas Docherty have welcomed the prospect of sharing a platform with David Cameron.
”We should focus on saving the Union,” said Mr Harris.
The row within Labour and hostility between Labour the Tories has handed the SNP a major boost as the referendum looms.
Commenting on the rift SNP MSP Kenneth Gibson said: ”It is supposed to be the season of peace and goodwill amongst all, but the unionist campaign is looking decidedly disunited.
”While David Cameron is welcome to front the anti-independence campaign, it will be interesting to see just how well received he is by the people of Scotland.
”Labour can’t decide if they should cooperate with Tories or not and they can’t even agree amongst themselves how can they be expected to give a consistent and clear message to the people of Scotland?
”There were reports last week the two main unionist parties were having secret meetings to stop Scotland moving forward, desperately trying to find a common cause to bind them and sell the out-of-date idea that the status quo is the best thing for Scotland.
”But their private meetings have resulted in public disarray only the SNP match the ambitions of the Scottish people and we will deliver the referendum on independence.”