Charles Kennedy is to lead the Liberal Democrat campaign opposing Scottish independence.
The former head of the party is to return to front-line politics, alongside the former Labour Chancellor Alistair Darling and the Scottish Tory leader Annabel Goldie, to become the public face against the expected referendum.
Confirming the unofficial appointment, Danny Alexander, the Chief Secretary to the Treasury and himself a Scottish MP, said: "Charles is going to lead the campaign. He is going to play a really, really strong and active role. He will be making the case from Scotland as part of the United Kingdom and part of the European Union. It is a huge argument. It's the biggest decision Scotland will make for many, many decades."
Writing last week in The Herald newspaper, Mr Kennedy urged Unionists across different parties not to become tribal in their fight against the campaign for Scottish independence, but to find "common cause" in defeating it.
"First, the more broadly based our campaign, the more likely its appeal," he wrote. "Second, in Alex Salmond, the pro-independence campaign has an inestimable leader, who allows little else to grow in his shade. We counter the cult of personality with political patience, perseverance and most of all persuasiveness."
Mr Kennedy, who was forced to resign the Lib Dem leadership after his battle with alcohol became public, has not played a prominent role in the Liberal Democrats since the Coalition Government came to power. But it is his distance from the Westminster administration that many strategists believe will be important in persuading Scottish voters not to back full independence from the union in the referendum expected before 2015.