ALEX Salmond will this week embark on the biggest gamble of his political career as he launches the campaign for a "Yes" vote in the independence referendum, knowing defeat would shatter the SNP and cut short his tenure as First Minister.

With opinion polls consistently showing most voters remain unimpressed by his party's core policy on separation, Salmond will unveil the Yes Scotland campaign in Edinburgh on Friday in the hope of winning hearts and minds by 2014.

With a £2 million war chest behind him, Salmond will appear with celebrities and cross-party political figures who will sign a Yes Declaration backing an independent Scotland.

Adopting the positive campaign tactics used by the SNP at the last Holyrood election, Yes Scotland, which includes the Greens and Scottish Socialist Party, is expected to promote independence as "historic", "exciting" and "transformational", while avoiding any use of the word "freedom" because of anti-English associations conjured up by the Mel Gibson film, Braveheart.

The campaign will be targeted at the 20% of swing voters the SNP have already identified as being crucial to the outcome of the referendum.

Dubbed the "Persuadables", they are open-minded about independence but as yet unconvinced.

To woo them, the Yes campaign will unveil a steady series of high-profile converts to independence, giving swing voters the mental "permission" to opt for change.

Well-known personalities expected to back the campaign include the actress Elaine C Smith and Scots-born comic-book writer, Mark Millar.

However, the ultimate factor in the campaign is likely to be the economy and whether voters believe independence will create or destroy jobs.

Friday's event will also see the launch of the Yes Scotland websites, and a campaign anthem understood to have been supplied by folk singer Dougie MacLean, writer of the much-loved ballad, Caledonia.

The venue – an Edinburgh cinema – has led to speculation that the capital's most famous independence supporter, Sir Sean Connery, might appear alongside the First Minister.

However, it is understood that Cineworld in Fountainbridge, the area of the city in which Connery was born, was only chosen at the last minute by Yes Scotland, as its first choice, the Citizens Theatre in Glasgow, was unavailable.

Despite polls suggesting only around a third of voters would vote Yes if the referendum was held tomorrow, Salmond has two-and-a-half years to make his case to the country and campaign funds of £2m thanks to a legacy from the late poet Edwin Morgan and a £1m donation from Largs lottery winners Christine and Colin Weir.

A further spur to Salmond is the knowledge that failure would devastate the party and make it all but impossible for him to carry on as a credible First Minister.

MP Angus Robertson, who masterminded the SNP's election campaign last year and who will play a key role in Yes Scotland, said: "The people of Scotland are open to voting yes as never before and that is a great starting point for the Yes Campaign. This campaign will be about the positive benefits of being independent, enabling us to build a Scotland that will be fairer and more prosperous than today."

The cross-party No campaign is expected to launch next month, with former Labour chancellor Alistair Darling playing a pivotal role alongside the former LibDem leader Charles Kennedy.

Deputy Tory leader Jackson Carlaw said support for Salmond and the SNP was waning.

"It is not enough for Alex Salmond to simply make a Braveheart cry for 'Yes' to separation when the SNP have repeatedly answered 'No' when asked fundamental questions as to what a separate Scotland would look like."

Scottish LibDem leader Willie Rennie repeated his insistence for a decisive referendum question.

"If he wants to win fairly he should agree to a cross-party committee to set the question."

The inclusion in Yes Scotland of parties with different views on what independence should deliver will be a test for Salmond, who is used to absolute loyalty within the SNP.

However, without them Yes Scotland risks being seen as little more than an SNP front.

Yes Scotland Ltd, the company behind the campaign, was set up last month by a solicitor working for the SNP and is based in the street behind Bute House, Salmond's official residence in Edinburgh.

Nine Yes Scotland websites have also been created by a woman working for SNP IT expert Mark Shaw, while a key Yes Scotland organiser is Jennifer Dempsie, a former adviser to the First Minister.