How challenging are SNP defections for Humza Yousaf?

Ash Regan came third in the SNP leadership race that was won by Humza Yousaf

Humza Yousaf's SNP has lost two parliamentarians in a month, to opposite ends of the constitutional spectrum.

First Lisa Cameron jumped ship to the Conservatives at Westminster, joining an avowedly unionist party, and then Ash Regan left the Holyrood group for a pro-independence rival in Alba.

How worried will the first minister be by these defections, and how damaging could they be for the SNP's future campaigning?

If you were to take the SNP's responses at face value, you would be forgiven for thinking they were almost glad to have lost an MP and an MSP in just over a fortnight.

There is often a spectacularly catty response to a politician jumping ship.

Humza Yousaf has been unequivocal in saying Ash Regan's departure is "no great loss".

He even claimed that she had no personal vote in her Edinburgh Eastern, and that anyone who had backed her had done so entirely because the SNP logo was next to her name.

This is reminiscent of the strong criticism of Lisa Cameron after she defected to the Conservatives; that too was supposedly "only a matter of time" according to briefing from SNP sources.

It extends to those ejected from the ranks too - Margaret Ferrier was written off as being "really hard of thinking" after her breach of Covid rules.

Such savage responses ignore the fact that the SNP knew exactly who all three of these women were, and selected them as candidates and campaigned to put them in office.

It's the nature of party politics. Yes, we'll tramp the streets to chap on doors on your behalf and post out leaflets with your face on, but if you become a liability or an opponent, no quarter will be given.

And in this case, the response belies a certain nervousness on the part of the party.

Not necessarily about the loss of Ash Regan personally, who had become a bit of a menace on the back benches since quitting Nicola Sturgeon's government over gender reform.

She had built a platform of her own during the leadership election, aided by former Alba strategist Kirk Torrance. The lack of surprise from SNP HQ is not feigned.

But there will be concern about the signal that it could send to pro-independence voters.

• Former SNP leadership candidate defects to Alba

• MP Lisa Cameron defects from SNP to Conservatives

The general trend in the polls was already suggesting a drift between support for the SNP, and support for independence.

The latter has held up firm in margin-of-error territory, while the SNP's numbers have declined somewhat from the dizzying highs of old.

In the wake of a chastening by-election defeat in Rutherglen and Hamilton West, the party is keen to shore up its pro-independence base.

It has promised to put independence on page one, line one of its manifesto for the next election, for all that the overall strategy is a reheat of Nicola Sturgeon's old "win the election and ask for a referendum" approach.

The party needs to cement its position as the dominant force in the Yes movement, particularly at a moment when every party is trying to badge itself as an agent of radical change.

Lisa Cameron defected to the Conservatives

Up until now, Alba have frankly not posed a threat of any kind to SNP hegemony.

Despite being led by Alex Salmond, the new party failed to get to 2% of the vote in the Holyrood elections in 2021 and fared no better in the council elections the following year.

Its only representatives were elected wearing SNP rosettes - two MPs at Westminster, and now an MSP at Holyrood.

But at a moment when the SNP is nervous about pro-independence voters toying with Labour or just staying at home, the last thing Humza Yousaf needs is Alba gaining some attention.

And Ms Regan - already styled as the Alba leader at Holyrood - will spend the rest of term walking in front of cameras and piping up in the chamber to bash her old party's commitment to the case.

The SNP is not particularly sad to lose Ash Regan, and it is not particularly scared of Alba, as things stand. But what does keep the leadership up at night is the idea that the pro-independence vote could drift away from them.

Rather than an issue about one individual MSP, it could be a blow to the party's overall electoral strategy.

Worrying symptoms

The same could be true of Lisa Cameron at Westminster. Again, her former colleagues have argued that they will not miss her as she crosses the floor.

But the fact of her defection will make it harder for the SNP to paint Labour as being the same as the Conservatives, when Sir Keir Starmer's party can point to a constituency where people literally voted SNP and got a Tory.

It's not about one MP personally - it's about the SNP's struggle with Labour to constitute the main anti-Tory vote in Scotland. A position the SNP has held in recent years, but fears losing.

As a bonus, Ms Cameron's departure was also the latest example of dysfunction in the Westminster group, which has also seen Angus Brendan MacNeil depart to sit as an independent.

There's also the question of momentum. The SNP's electoral juggernaut used to roll downhill with seemingly unstoppable force.

Now the engines are spluttering, and rather than establishing his new leadership Mr Yousaf faces questions about how he will turn things around.

As with the drip-drip of by-elections at Westminster, these defections don't seriously threaten his government's majority or current standing atop the pile in politics. But they are worrying symptoms of problems that Mr Yousaf will not want to grow.