Stephen Flynn has insisted that Humza Yousaf is doing a "brilliant" job despite the problems facing the party.
The SNP Westminster leader said that the First Minister had made the right decision by putting the cost-of-living crisis "front and centre".
Flynn admitted that Yousaf's first hundred days in office have been "challenging".
He has had to deal with the police investigation into the SNP's finances, which saw former First Minister Nicola Sturgeon arrested and released pending further investigation.
He has had two big policy u-turns on the deposit return scheme and highly protected marine areas and the gap between the SNP and Scottish Labour has been narrowing in the months since Sturgeon resigned.
A recent Holyrood poll put Labour just three points behind the SNP in the constituency vote and just two points behind in the regional vote. This is the closest that the parties have been in more than a decade.
But Flynn told Sky News: “despite the challenges that we face, we still enjoy a fairly comfortable poll lead over the Labour Party and a huge poll for the Conservative Party which comes as no surprise to anyone in Scotland.
“Perhaps more importantly, when it comes to the independence numbers in Scotland, we are still roughly where we were before all this started, around about 50-50, give or take a few percent here or there.
“That gives me a lot of cause for hope and a lot of cause for optimism.”
Asked how Yousaf is fairing as First Minister, Flynn said: “I think he’s doing brilliant.”
He added: “It's been a bit of a challenging time for the party, to say the least.
“We've had the difficulties internally, but I think Humza’s come into it and what he has done is put the cost of living crisis front and centre because I think all of us at this moment in time recognise that that's the biggest challenge facing people.
“And of course, when that is the biggest challenge government needs to respond accordingly and within the powers that the Scottish Parliament have, Humza has sought to do that.”
When asked if the party's u-turns marked a "shambolic" start to Yousaf's life as First Minister, Flynn said
Flynn said: “It looks like he's a First Minister who wants to set his own agenda.
“And I think that's really encouraging.”
He added added: “What Humza has sought to do is to reset our relationship with business - something which he's done, he's done very well, very quickly.
“He's also sought to listen to the views of communities who would have been impacted by the likes of the HPMA proposal.”
Flynn said he was “pretty optimistic” of the SNP's chances at the general election.
The party's Westminster group has also had its own issues, with senior MP Angus MacNeil suspended for a week after branding chief whip Brendan O'Hara a "bully".
Six SNP MPs have so far announced they are standing down at the next election. Among these are three of the groups most high-profile figures.
Former Westminster leader Ian Blackford, ex-party deputy leader Stewart Hosie and current deputy Westminster leader Mhairi Black have all announced that they will not be seeking re-election.
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