As far as metaphors go it was a bit on the nose. 

Shortly after Thursday’s First Minister’s Questions, SpaceX's new rocket, Starship blasted off from Boca Chica in Texas, soaring to just under 25 miles before exploding spectacularly. 

It was, the firm said, a “rapid unscheduled disassembly before stage separation.”

READ MORE: Space X rocket blows up in 'rapid unscheduled disassembly'

After the last few weeks, the SNP know a thing or two when it comes to rapid unscheduled disassembly.

Humza Yousaf and his party are now bracing for much worse to come, and, according to sources in the party, there’s a fear that much worse could come as soon as this week.

Following the arrest of former chief executive Peter Murrell, the national treasurer Colin Beattie, the next person to be helping Police Scotland with their enquiries could be the third person named on the party's accounts, Nicola Sturgeon.

The SNP wasn’t saying if the former first minister would be in parliament this week. 

She missed last week’s business, voting remotely rather than in person. 

At the time, her spokesperson said she was staying away “to ensure the focus of this week is on the new First Minister setting out his priorities for the people of Scotland.”

The focus of the week was not on the new First Minister. 

He and his colleagues have been candid about their frustrations that their new administration has been completely overshadowed. 

“It's frustrating, obviously,” Wellbeing Economy minister Neil Gray told The Herald on Wednesday. “We're not able to talk as much about the priorities that we're setting out for government because some of the party issues are dominating.”

Mr Yousaf has, the SNP’s former head of communications, Fergus Mutch said, been dealt “the duffest of duff hands” when it comes to trying to set the agenda.

If Ms Sturgeon were to be questioned, that’s only going to get harder. 

“You know, frankly, if a former first minister is arrested and questioned on the same basis, as the two other members of the SNP so far, that will make Peter Murrell's arrest, that will make Colin Beattie's arrest look like a slow news day," Mr Mutch added.

With poll ratings for the party falling, the beleaguered fledgling party chief needs to get on the front foot. Or, the former aide warned the knives could soon be out. 

READ MORE: SNP finances whistleblower calls for inquiry into police response

And while the First Minister has been upfront about the problems facing the SNP, some of his supporters fear it could now be starting to define him. 

“I’m haunted by that clip of him saying he didn’t believe the SNP was a criminal organisation,” one MP who backed him in the leadership contest said. “The answer should have been no, the SNP is not a criminal organisation.”

There is a lot of sympathy for the First Minister among his colleagues, even those who didn’t back him.

“But that’s not great, is it” said the MP, “feeling sorry for the person who’s leading the country?”

Mr Yousaf’s attempt to take back the agenda on Tuesday with his new prospectus and three-year plan for government was completely derailed by the arrest of Mr Beattie. 

“You had what would have, with a bit of space around it, been, I think, a pretty popular reset in terms of the relationship with business, in terms of ditching a few unpopular policies, in terms of getting rid of some of the things that become a bit of a distraction for the Scottish Government,” Mr Mutch said. “And unfortunately for Humza that was completely overshadowed by events.”

On Friday YouGov published a new poll showing that support for the SNP had slumped to its lowest level since the 2014 referendum on independence. 

READ MORE: Poll Scotland: SNP support 'falls to lowest level since Indyref

According to Ballot Box Scotland, the SNP would lose 13 seats at the next Holyrood election, including Mr Yousaf’s Glasgow Pollok constituency. 

They would, with 51 seats still be ahead of Labour’s 34, but the gap is closing.

In December, YouGov had the SNP winning 50 per cent of the Holyrood constituency vote, in last Friday’s poll that was down to 38%.

The poll also found that only 19% of Scots believe Mr Yousaf is doing well, with 44% who believe he is doing badly.

One in three Scots are still currently unsure how he is doing as First Minister.

“The polls are not going in a helpful direction for him,” Mr Mutch said. “And in politics, that momentum, when it turns against you it can be a really, really hard thing to fight against.” 

“It will be interesting to see whether he can level out what's happening with the polls right now and if he manages to do that and sustain SNP support above Labour at current levels, and then perhaps the heat comes out of some of the issues surrounding the SNP right now, then he's got an opportunity.

“The really, really difficult point I think becomes at the point the balance tips.

"So one, if the SNP slips beneath Labour in the polls, then that's tricky because Labour will sense opportunity and as I say, it's hard to fight against momentum in politics, and people will look at Labour as a realistic prospect for beating the Tories next year, of course, but potentially, as a future Holyrood government again. 

“The other part of that is if SNPs support dips beneath Labour, then the knives are out slightly within the SNP. 

“He was not starting from a position of absolute dominance within the party. Kate Forbes managed in the final round to take almost half the vote share.”

Mr Yousaf’s next electoral test is likely going to be the by-election in Rutherglen and Hamilton West. 

Though Margaret Ferrier has appealed the 30-day sanction, there’s little expectation that she’ll be successful.

Any recall petition and vote will now almost certainly be in the autumn.

But the cash-strapped party could soon find themselves facing at least one more by-election, possibly even two.

SNP members in Nicola Sturgeon’s Glasgow Southside constituency think it’s unlikely she’ll stay on as the MSP for the next three years.

The next branch meeting is around a fortnight away, and some think she could use that as an opportunity to let local activists know her plans. 

There is still a huge amount of support and loyalty for the ex-leader. 

“I'd say a lot of us are still unclear what exactly the 'criminality' is supposed to be,” one member told the Herald on Sunday.

“But bad decisions that we don't understand and accounts signed off by the auditors, what's the crime supposed to be? All very confusing.

“And we wish the likes of Humza and Shona would hold their tongues and not be seen to jump to conclusions as quickly as they seem to be at present.”