Humza Yousaf had a specific group of Scots in mind as he kicked off the SNP's general election campaign today.

The demographic in question is independence supporters who may now be toying with idea of backing Labour at the next Westminster ballot to remove the Conservatives from power.

UK Labour leader Sir Keir Starmer and Anas Sarwar, the Scottish Labour leader, have been wooing this group - what one commentator has described as "scunnered Yessers" - for some time.

READ MORE: Yousaf tells independence supporters they 'must' vote SNP

And judging by their party's victory in the Rutherglen and Hamilton West by election in October and quite a number of opinion polls they have done so to date with considerable success.

The vote in South Lanarkshire saw a 20% swing from the SNP to Labour while polling has identified that while support for independence remains around 50%, support for the SNP is significantly lower.

Ipsos Mori's latest poll back in November did bring good news for the SNP showing the party was 10 points ahead of Labour for Westminster votes despite the myriad of challenges which hit the party last year.

The Herald: First Minister Humza Yousaf launching the SNP's General Election campaign in Glasgow today. Photo Gordon Terris/The Herald.

But the more worrying aspect for the party was that while it showed 54% support for independence, only 40% of voters said they would vote SNP if there was an immediate General Election (5 points lower than the 45% who voted for the the party in December 2019).

Hence the drive to win back these straying voters, before it's too late and they either become non voters, supporters of other smaller independence parties, such as the Greens or Alba, or become Labour supporters.

READ MORE: FM to pitch for 'Tory-free Scotland' at SNP election campaign launch

The First Minister's pitch was forceful.

"This election represents an important moment for Scotland’s independence movement," he told the audience at Oran Mor in Glasgow's west end.

"Keir Starmer will use every vote for Labour in Scotland as a vote against independence. He will argue that every vote for Labour is a vote of confidence in Westminster control.

"So if you believe decisions about Scotland should be taken in Scotland – if you believe in independence - you must vote SNP.

READ MORE: FM would continue deal with Greens even if SNP lose more than 15 seats

"If you want to see an independent Scotland, you have to get out and vote for it."

The First Minister's words echoed the argument made by SNP MP Tommy Sheppard last weekend which was again an appeal to Yes voters considering either not voting or even voting for Labour.

Writing in the Sunday National Mr Sheppard spelt out the implications of the General Election going badly for his party with a call for independence supporters to unite.

He noted: “If the SNP lose the election in Scotland, the debate on independence stops. That is why we must put aside our differences and unite.”

The SNP's hope of course is that by laying down the stark consequences for the independence cause of the party doing badly at the General Election, disillusioned Yessers will sit up, take note and say to themselves 'well I better vote for the SNP again otherwise there's no hope of independence.'

It's a strategy which of course might just work. The polls are tight between the SNP and Labour and such a shock tactic may well prompt enough independence supporters to vote again for the SNP.

However, there are problems with it too, in particular it's a tactic that doesn't seem to appear to take any heed of why the SNP has lost appeal among some Yes supporters.

For some it may be that they feel let down, that they have voted numerous times for the SNP since the 2014 referendum, and while the party has been victorious at successive elections, no progress has been made on independence.

They may think 'you made promises on holding a new independence referendum and taking us back into the EU, but not managed to deliver it. So why vote for the same thing now?'

Others may have misgivings about the SNP's record in government, whether its management of the NHS or education, cuts to public services that are coming down the line with the budget, or policies such as gender recognition reform.

A message commanding independence supporters to vote for the SNP without the party appearing to be ready in return to listen could well backfire.

And the danger is if the party appears not to want to pay attention, voters will make their views known at the ballot box.