Support for the Bute House agreement has fallen among SNP supporters, according to a new poll.

Survation found that 48% of Scots who voted for the party in 2019, backed the deal, down ten points since May. 

Another 24% of SNP voters were opposed. 

In total, 28% of Scots supported the deal, while 40% were opposed. 

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The poll, carried out for the True North political consultancy, also found some startling regional variations. While it was backed by 29% of voters in Glasgow, and 34% of voters in Lothian, in the North East it was just 19%. 

However, in the Highland and Islands, where there has been vocal opposition to controversial Green policies including the Highly Protected Marine Areas, the support for Patrick Harvie’s party remains consistent with the Scottish average, coming in at 26%.

Though it was opposed by 44% of voters there, compared to 31% in Lothian and 35% in Glasgow. 

The Bute House Agreement gives the minority SNP group in Holyrood a parliamentary majority and helps protect them from votes of no confidence.

As part of the deal, there is a joint policy platform covering a wide range of areas, including independence, housing, transport and tackling climate change.

When it was first put to the party by Nicola Sturgeon following the 2021 election, it received the support of around 95% of SNP members.

However, in the years since a number of policy failures have caused tensions, particularly the chaotic and delayed Deposit Return Scheme (DRS).

A number of SNP politicians and former Scottish Government ministers have criticised the pact in recent weeks. 

Former finance secretary Kate Forbes suggested the party should “check-in” with members about the content of the deal, while Fergus Ewing has called for it to be jettisoned altogether. 

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Addressing a briefing held by True North on Tuesday morning, Professor Sir John Curtice said the dissent over the arrangement had an impact on public opinion. 

“I mean, it wasn’t particularly wildly popular when Survation asked his back in May, it was 36% in favour, 37% against. 

“But again, you have to bear in mind that given only half the people who voted in 2021 voted for the SNP or Greens, that's pretty much what you'd expect, because opposition voters are going to tend to say it sucks and people who voted for the SNP greens are going to be inclined to say it's okay. 

“But now you're looking at 28% saying they’re in favour. 

“Yes, some of that movement is undoubtedly amongst opposition voters supporters, particularly amongst those who voted Conservative, surprise, surprise. 

“But it's also the case that there's been a movement since May amongst those who voted for the SNP in 2019. 

“Back in May, 57% of 2019 SNP voters said they thought they said they supported the deal it's now down to 48%. 

“Now, there's been no great drop in SNP support since May, about a point or so. So I don't think we can necessarily say that this is something that's particularly pushing SNP support down. 

“But that said, it is clear that the internal arguments have indeed had some impact on SNP voters, although it's still the case, that twice as many SNP voters approve the deal as disapprove. 

“But there is a non-trivial minority of SNP support, who are not that enamoured of the deal that it is currently ruling the roost of Hollywood.”

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Prof Curtice said the poll which had the party on 9% of the list vote at Holyrood, showed the Greens were “basically doing okay out of being in government.

“Unlike the Liberal Democrats in Westminster between 2010 and 2015, but perhaps much more like the Liberal Democrats at Holyrood between 1999 and 2007, being in coalition is not doing the Greens any harm. 

“The 9% figure in this poll is a little bit on the low side as compared with many recent poll but it's still above what they got on the regional list last time. 

“And we have to remember, the Greens are appealing to a relatively small niche market, and whatever is the wider flack going on, and it's essentially now within the SNP about the merits of the deal, that's not necessarily flack that particularly impresses those who are minded to vote for the Greens on the regional vote.”

Eilidh Whiteford, a senior adviser at True North, and the former SNP MP for Banff and Buchan said the polling showed a real split. 

She said that while the deal was "reasonably popular with young urbanites in the cities of Glasgow and Edinburgh" it was a "different story when you get out to rural and small towns in Scotland." 

Dr Whiteford pointed out that "less than half of SNP voters at the last General Election support the deal and around a quarter actively oppose it."

She warned that the deal could be a problem for Humza Yousaf's party.

"It might not be a deal-breaker for SNP voters but it might suppress turnout."

The ex-politician warned that it could make it hard for the SNP to capitalise on the relative weakness of the Tories in more rural areas.