The general election campaign is well under way and opinion polls are coming thick and fast.  

Almost every day new surveys are issued gauging people’s voting intentions as the electorate hurtles towards polling day on July 4.  

The most recent poll in Scotland shows that Labour are on course to replace the SNP as the biggest party, though John Swinney may have stopped his party’s slide since he replaced Humza Yousaf as First Minister.  

Current polling suggests Labour are on course to win between 28 and 30 Scottish seats, up from their current two. 

The SNP’s cohort at Westminster could fall to between 16-18 MPs, while the Liberal Democrats would take five seats and the Tories six. 

The current predictions are a far cry from the SNP’s domination of Scottish politics in recent years, with the party returning 48 MPs from Scotland’s 59 constituencies in the last general election in 2019.  

There has been a lot of water under the bridge since then, with all major parties changing their leaders – in the case of the SNP and the Conservatives, more than once.  

So what has caused the slide down the polls? Our exclusive graph looking at polling data across the past five years since the last election shows that the party has been squeezed by factors outwith its control.  

But it has also blundered into losing the trust of the public, with its former voters deserting it at key times.  

The Herald: First Minister Nicola Sturgeon celebrates with supporters at the SEC Centre in Glasgow during counting for the 2019 General ElectionFirst Minister Nicola Sturgeon celebrates with supporters at the SEC Centre in Glasgow during counting for the 2019 General Election (Image: PA)

The highest of highs.  

After the dust had settled following the general election in 2019 – which returned Boris Johnson as Prime Minister with a majority of 80 MPs - the SNP was riding high in the polls. 

Nicola Sturgeon was leader of the party and First Minister, and enjoyed support of around 45% of the electorate, according to pollsters.  

READ MORE: Scotland wide poll predicts disaster for SNP

This would grow to 50% during the pandemic which gripped the world over the following years, with Nicola Sturgeon widely praised for her forthright response to the challenges faced by Covid and lockdowns.  

The party’s popularity was reflected in 2021, when it retained the Airdrie and Shotts seat with the election of Anum Quisar with 46% of the vote. This byelection was the first to be held in Scotland since 2011.  

First signs of the slump  

It was the tumultuous events of the spring and summer of 2022 which first caused a major jolt in opinion polls, with the SNP and the Conservatives losing ground to Labour. 

Despite his unpopularity in Scotland, Boris Johnson kept the Conservatives on an even keel down south until Partygate revelations saw the Lib Dems launch a vote of no confidence in the Prime Minister in April that year. 

Although he survived, a large rebellion appears to have given voters belief that Sir Keir’s Starmer’s Labour would be a better bet for office, with the growth in his party’s popularity stemming from this date.  

Johnson’s resignation as Prime Minister in July saw a further rise for Labour at the expense of other parties, while the short-lived Premiership of Liz Truss cemented the surge.  

The Herald: Sir Keir StarmerSir Keir Starmer (Image: PA)

Picking up speed  

With the probe into the SNP’s finances - Operation Branchform – ongoing since 2021, seemingly never-ending problems with the ferry network and the controversy around the Gender Reform Recognition Act, the SNP has faced problems of its own in keeping itself on the right side of voters.  

Polls show a steady decline in support since the start of 2023, and Nicola Sturgeon’s resignation in February did nothing to halt the decline. However, her arrest in June that year as part of the investigation into the SNP’s finances was the catalyst for Labour to finally catch up, with the two parties neck-and-neck at that point.  

The election of Humza Yousaf did little to affect the SNP’s fortunes, with support steadily drifting away across the year he was First Minister. 

Labour would capitalise on their opponent's malaise during this time by winning the Rutherglen and Hamilton West by-election sparked by the recall of disgraced SNP MP Margaret Ferrier.  

According to the polls, the SNP’s popularity slumped from a high of 40% during his time in charge to a low of 31% by the time he left office.  

The Herald: Humza YousafHumza Yousaf (Image: PA)

Can the SNP come back?  

Over time, the direction of travel for the SNP has been in one direction. Pushed by voters looking for an alternative to the Tories, and by mistakes of their own making, the party's support has simply whittled away. 

However, the most recent poll, by Savanta for The Scotsman, found that the ship has steadied in the month since John Swinney became First Minister. 

While the SNP are still behind Labour, there has been no further fall and the party has regained the lead in voting intention for Holyrood.  

Chris Hopkins, Political Research Director at Savanta said: “Our first poll since John Swinney was confirmed as Scotland’s First Minister suggests that he has managed to stem the SNP’s bleeding. 

“In a sense this is positive news for the SNP, but is also a likely consequence of him simply not being Humza Yousaf.” 

The Herald: John SwinneyJohn Swinney (Image: PA)

The party will also take heart that there is still a long way to go until the general election, and time yet to get voters back onside.  

Tellingly, support for independence remains strong – with the country still split pretty much 50/50 on the issue.  

READ MORE: John Swinney has 'stemmed the bleeding' of support for SNP

If the SNP, the party of independence, can bring these voters back then it will be able to stem its losses in the face of a resurgent Labour.  

Of the recent polls, polling guru Professor John Curtice said: “The party’s support for Westminster is as much as four points down on the beginning of the year. 

“Fewer than two in three of those who would vote Yes in an independence referendum are currently minded to vote for the party. 

“As a result, Labour now have a clear lead in Westminster vote intentions for the first time since the 2014 independence referendum. 

“As the General Election campaign gets under way, the SNP face the prospect of severe losses at the beginning of July, and thus the possible loss of its coveted status as the third largest party at Westminster. 

“The party badly needs to try and persuade Yes supporters to return to the party fold.”