LABOUR all but conceded defeat in the Aberdeen Donside by-election last night, as senior party sources said they were not expecting an upset in a seat with a 7000-vote SNP majority.

Bookmakers William Hill predicted a "Donside doddle" for the SNP's Mark McDonald, quoting odds of 33/1 on, compared to 10/1 for a Labour win, and all other parties at 150/1.

Labour pessimism was underscored by Johann Lamont's decision not to campaign in the city over the final weekend of the by-election. Labour's leader is not due there until Tuesday.

In contrast, SNP leader Alex Salmond and his deputy Nicola Sturgeon were yesterday in Donside, which the party hopes to retain following the death of MSP Brian Adam in April.

Adam took the constituency from Labour in 2003, increasing the SNP's majority until, in 2011, he won 55.4% of the vote compared to Labour's 28.5%, and had a majority of 7175.

Confident of victory in what has become a two-horse race, SNP insiders say their main objective is to maintain that vote share.

Labour has thrown resources and some big names into the fight, with deputy UK leader Harriet Harman knocking on doors last week.

Defeat on home turf would be a hammerblow to the SNP ahead of the independence referendum, and end their majority, on paper if not in practice, at the Scottish Parliament.

But Labour was last night downbeat about the prospects of candidate Willie Young, the finance convener on Aberdeen City Council.

A senior campaign source said: "People don't want to vote for the SNP. They don't like Salmond or independence, but they also don't have a big reason to vote Labour yet. We might pick up a bit, but people are not exactly rushing to us."

Although the by-election was initially seen as a "referendum on the referendum", the campaign has been dominated by local issues, such as school closures and traffic congestion.

McDonald, who resigned as a list MSP for the North East to fight the seat, has attacked Young's local record, as well as his support for tuition fees and his views on ending the council tax freeze.

In response, Young has accused the SNP government of short-changing Aberdeen through the local government funding system, and of dragging its feet on the upgrade of the choked Haudagain roundabout, where delays cost the economy an estimated £30 million a year.

Although a classic two-way fight, Thursday's result also matters to the smaller parties. Tory Ross Thomson will be hoping for a lift under Ruth Davidson's leadership, while LibDem Christine Jardine will be scrabbling to avoid another lost deposit for the party.

The showing of UKIP's Otto Inglis is also hotly anticipated, given the breakthrough wins for Nigel Farage's troops in the recent English council elections and the SNP's insistence that UKIP is an irrelevance north of the border.

In 2011, UKIP logged 0.8% of the list vote in the seat; this time it could be nearer 10%.

Campaigning with around 200 SNP activists in Bridge of Don yesterday, Salmond said he was "extremely pleased" with the response.

"People are also well aware of the contrast between Mark McDonald as a proven local champion, and his gaffe-prone Labour opponent. We are very optimistic but not complacent."

Young said: "Despite running scared of the issue for the last few weeks, we know Alex Salmond and the SNP will take every vote as an endorsement for breaking up the UK. That is why I am asking people to send Alex Salmond a message – we don't want independence, we want a parliament that will reflect the priorities of this community, not the SNP's."

LibDem Jardine added: "The SNP have got their priorities all wrong. They need to spend less time preaching about independence and more time delivering for families and businesses in Aberdeen."

Thomson said: "This is an opportunity to elect a local champion who will fight Aberdeen's corner in the Scottish Parliament."