It was a job many senior SNP politicians were reluctant to go for but when Nicola Sturgeon phoned Humza Yousaf to let him know that the next morning she would be announcing her decision to resign there appeared to be little doubt in the health secretary's mind that he would run to succeed her.

During the course of the subsequent leadership contest it became clear the Glasgow Pollok MSP was the first minister's choice with key members of her government endorsing his candidacy.

His closeness to Ms Sturgeon was a critical advantage for Mr Yousaf during the bitter campaign against finance secretary Kate Forbes and former community safety minister Ash Regan, both of whom wanted to take the party in a different direction from Ms Sturgeon.

Yet days after Mr Yousaf was sworn in as Scotland's sixth first minister, a police tent was erected in his predecessor's front garden and her husband Peter Murrell was arrested and questioned by detectives for 12 hours as a long running police investigation into SNP finances took a dramatic new turn.

READ MORE: Ten dates in Humza Yousaf's time as SNP leader ahead of 100th day

A couple of weeks later the party's then treasurer Colin Beattie was arrested with Ms Sturgeon arrested and questioned too earlier this month. All three were released without charge while the police continue their inquiries.

The events plunged Mr Yousaf's new government into crisis mode with the prospect of any honeymoon period Mr Yousaf may have expected to enjoy as a new leader vanishing.

Many observers have said that Mr Yousaf was dealt a bad hand as he began his period in office but as he approaches 100 days as party leader and First Minister on Wednesday and Friday this week the key question is, could he have played his bad hand better?

The Herald:

Police officers pictured about to enter the SNP's headquarters in Edinburgh on April 5. Photo PA.

Could he have navigated the unprecedented challenges he inherited more smoothly and what of his record on government policy? Is the independence case advancing? And just how long is Mr Yousaf likely to be SNP leader and first minister?

Some believe Mr Yousaf would have benefited from putting greater distance between himself and his predecessor. But he appears to have been reluctant to do so.

While another politician may have been a little reticent to sing Ms Sturgeon's praises, the first minister had no such qualms describing her, following her arrest, as "the most impressive politician I think we’ve seen in Europe".

READ MORE: Analysis: Is Yousaf's indy strategy just a SNP damage limitation plan?

It's a view now out of step with public opinion north of the Border with recent polls suggesting the former FM's popularity has plummeted. 

Last month polling company Panelbase found that her personal popularity had fallen by 38 points since February, shortly after she resigned as first minister and when it last asked voters whether they thought she was doing a good job. At that time she recorded a plus 20 rating but in its most recent research, conducted after her arrest, she scored minus 18.

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Nicola Sturgeon speaking to journalists in Holyrood in April. Photo PA.

James Mitchell, professor of public policy at Edinburgh University, and the country's leading academic authority on the SNP, said failing to remove the whip from Ms Sturgeon following her arrest and the ongoing police investigation, made him look weak and indebted to her. He is among those who believe the first minister would be in a better position had he acted more robustly.

"He looks weak and indebted to Sturgeon. Suspending the former leader would not only be consistent with how she behaved but also would have shown leadership and a willingness to be his own person," Professor Mitchell told The Herald.

"Sturgeon has not helped at all. She should have resigned her membership on the understanding that this was so long as the enquiry continued. His loyalty to her has well outstripped her loyalty to him and the SNP. She has placed him in a very difficult position."

There is also the belief in SNP circles that he took too long to ditch unpopular policies from the Sturgeon era.

The Herald: Kate Forbes has praised what she described as the Scottish Government's new approach to HPMAs

Former finance secretary Kate Forbes pictured in Holyrood.  Photo PA.

Only the proposed ban on alcohol advertising met a swift end with the controversial deposit return scheme and the plan to ban fishing in at least 10% of Scottish waters under the highly protected marine zones proposal allowed to linger on for weeks.

The HPMA plan was finally dropped on Thursday to the glee of fishing communities around the country - as well as SNP front and backbenchers. Ms Forbes, Ms Regan along with health minister Maree Todd were among those who welcomed the announcement.

But some note that by keeping such policies for several weeks the perception was given that he was still wedded to Sturgeon's policy agenda and reluctant to give it up. Had he axed them sooner he would have given the impression of a leader taking decisive action, some say.

READ MORE: 'Yousaf looks weak and indebted by not suspending Sturgeon from SNP'

The lack of speedy action on dropping the policy was noted by Mr Salmond's former advisor Geoff Aberdein who wrote on Twitter: "It shouldn’t have got to this stage in the first place but a good sign the new FM is listening and responding positively  to concerns of an industry that is vital to our coastal communities."

And what of the NHS? It's Scottish voters top priority yet Mr Yousaf and his team have yet to come up with any robust plans to bring down waiting lists. Last week waiting times for cancer treatment were at an record high. In the first three months of this year, only 69.4% of patients were seen in 62 days, down from 71.7% in the previous quarter. The Scottish Government's target is for 95% of patients to start receiving treatment within 62 days of being referred by a GP or screening service with an urgent suspicion of cancer.

"He needs to get a grip on the policy failures he inherited. This was not going to be easy of course but he needs more focus on everyday concerns of Scottish citizens," said Professor Mitchell.

On independence, the senior academic was unconvinced about the First Minister's plan. At the SNP's convention at Caird Hall in Dundee on Saturday last week Mr Yousaf put independence central to his party's general election strategy saying if the party won in Scotland that would be a "mandate for independence".

READ MORE: Humza Yousaf: SNP support in Rutherglen and Hamilton West ‘rock solid’

"There is not going to be a referendum any time soon and he needs to show leadership in confronting his party with this reality," said Professor Mitchell.

"He also needs to start addressing the weaknesses exposed in the case for independence during the 2014 independence referendum. The focus on referendums and mandates is evasive, a means of dodging difficult questions – a focus on process rather than substantive issues.  The Caird hall event was more of the same – lots of people talking to themselves and ignoring legitimate concerns people have about independence."

Professor Mitchell's views on a need to advance the independence case by focusing on the changes it would bring rather than how it can be achieved were echoed by some in the party.

"In taking the independence argument forward we really need to get away from the process and focus on what difference it will make to people’s lives. I think that is something that is coming through," said one senior SNP source.

"But that has to go hand in glove with actual delivery on the ground from the Scottish Government. I think that is one of his most pressing priorities and needs to be more of a significant feature. I think if the government is delivering well that enhances the argument that we could do even better with independence.”

Former first minister Alex Salmond repeatedly made the argument ahead of the 2014 that competent government would help persuade voters of the case for independence.

The insider added: "It doesn’t come down to one person, but that was felt to be a winning formula. That has got to come more to the fore as time progresses."

What has worried some in the party is polling showing the association between independence supporters and the SNP beginning to break.

Several surveys have shown that while support for independence is around 45% to 50%, support for the SNP hovers around 38%.

The hope among party strategists is that with a renewed focus on independence these soft Yes voters will come back. A likely Westminster by election in Rutherglen and Hamilton West following the recall petition for Covid breach MP Margaret Ferrier, a former SNP MP who now sits as an independent, will give a real indication of whether the plan is working.

But of course the big test will come with the general election expected in autumn 2024.

Some around Holyrood believe that if the SNP is defeated next year by Labour such a result would mark the end of Mr Yousaf's shift as party leader and first minister.

There is an expectation Mr Yousaf would step down at that point with Ms Forbes under pressure to pick up the reins and lead the party into the Holyrood election 18 months later.

However, it's not a view shared by everyone in the party.  Some fear if Scottish Labour do well in the general election, momentum may be on Anas Sarwar's side ahead of the Holyrood poll. The question some are now asking is who would want to take over when the party is facing the loss of power in Edinburgh?

"I think the seat loses next year will rally the party around Humza for 2026, including Kate [and her supporters]. Even his biggest detractors don’t want to take over when the party is probably on the slide. I imagine they might want to take over after 2026 to rebuild," according to one observer who thought the SNP could well be facing a Holyrood defeat with a governing deal struck by Labour, the Lib Dems and Tories.

"If Labour do well next year they will claim they have momentum in the run up to 2026. I think it’s likely to be an Edinburgh city council situation as in Labour and Lib Dems backed up by the Tories."

Should that scenario come about 2026 would be the year the SNP are out of power for some years. It would not only be a massive blow for Mr Yousaf but bring a devastating end to the party's independence ambitions for a considerable period.