In the oil-rich north-eastern constituency of Aberdeen South, Scottish National Party (SNP) MP Callum McCaig is trying to stay calm and carry on campaigning.

His seat, which he won in the 2015 election with a 14.9 per cent majority, is said to be at risk of falling to the Tories, which last held this Scottish constituency in 1992.

A sign of the Tories' optimism - Prime Minister Theresa May stopped by on her first trip to Scotland while on the campaign trail.

Nearly 60 per cent of Aberdeen City said no to independence in 2014, and one in three is believed to have voted for Leave. The Conservative Party is counting on this to get them through to Parliament, with its candidate's poster reading "Vote Ross Thomson to stop indyref2".

Mr McCaig, 32, said a second independence referendum is not the dominant issue, as his political rivals would like to make it out to be.

He said: "A few people said, based on the campaign so far, it's a bit laughable that SNP is accused of being obsessed with a second referendum when it is the other parties who keep harping on it, asking voters leading questions on the doorstep."

But while oil and gas brought great wealth to the city, the recent plunge in oil prices has hit residents hard. Many have lost their jobs, some have lost their homes. And that has had a trickle-down effect to even nail bars and hair salons which have been hit by poor business, said Ms Ione Gilmour, 57, whose neighbourhood in Ellon is home to many oil workers.

Mr McCaig insists the oil crisis has not changed the election game and the slump has changed people's lives more than their voting intentions. "Most people are aware of what SNP has done to support them, such as moving them into new industries, investing in innovation and diversification. I don't get a sense of a large number of people changing their votes."

About 200km south of Aberdeen, the Labour Party could be at risk of losing its only seat in Scotland.

Edinburgh South has been a Labour stronghold since 1987, but MP Ian Murray, 40, had a majority of only 5.4 per cent in the last election. With other parties such as the Greens, Ukip and Scottish Socialist not running this time, those votes will be split between Labour, SNP, the Liberal Democrats and Tories.

Labour hopes unionist voters from the Liberal Democrats and Tories will vote tactically for Mr Murray to keep SNP out. But the city voted overwhelmingly to stay in the EU and that might work in the favour of SNP, which has promised to fight for Scottish interests when it comes to the Brexit negotiations.

"Some parts of this constituency are quite anti-SNP, and Labour has been here a long time," said retiree Sheena Ostrowski, 65.

She is confident Mr Murray will keep his seat. "But if the last year showed you anything, it showed you anything can happen."