LABOUR hit the streets of Glasgow East over the weekend as activists banged on 20,000 doors in a final effort to shore up the party's vote.
But Labour's campaign managers seemed keen to play down expectations on the size of victory they expect despite a poll over the weekend suggesting they had 52 per cent support in the constituency as against 35 per cent for the SNP. They suggested that the final gap might be much tighter.
By contrast, Alex Salmond, the First Minister and SNP leader, was still predicting "a political earthquake" with his party winning in what was Labour's 25th safest seat as he brought in four more high-profile backers including veteran Clydeside trade unionist Jimmy Reid, now a member of the SNP.
But apart from the SNP, political opponents were privately conceding that Labour will probably win the crucial by-election, suggesting the party was deliberately playing down expectations to nullify the effect of a much-reduced majority from the 13,500 lead they enjoyed in 2005.
A Conservative campaign insider said: "It's a classic damage limitation exercise by Labour. Alex Salmond has played into their hands by raising expectations of an SNP victory. Labour will hope a win is good enough, even though in reality a much-reduced majority in a safe seat is a disaster for them."
The claim was denied by a spokesman for Labour's candidate, Margaret Curran.
"What we are saying is that the only poll that matters is the one on Thursday," he said.
In a television interview over the weekend, Mr Salmond insisted his party was on the verge of a historic victory and reminded viewers that the Glasgow East seat is safer than that of Gordon Brown's own constituency, Kirkcaldy.
He also seized on weekend reports of chaos and dispirited workers within the Labour by-election campaign team.
One of the campaign organisers, Martin Rhodes, was quoted as describing Mr Brown's leadership as "disappointing" and as saying the result would be "scarily close".
Mr Salmond said: "The Labour campaign is in chaos. Our campaign is optimistic and upbeat. I'm optimistic, upbeat, and the earthquake is on the way. The ground in Glasgow East is shuddering."
SNP activists yesterday delivered 10,000 letters from Mr Reid, explaining why voters should switch to the Nationalists.
Meanwhile, the actors Martin Compston and David Hayman joined the artist Peter Howson in declared their backing for the SNP.
Despite the importance of the by-election, which could see Mr Brown forced to quit as party leader if Labour lose, the party's campaign manager, Scotland Office minister David Cairns, said activists were in good spirits.
"We will be pounding the streets relentlessly from now until 9:55pm on Thursday night," he said.
"We are in very good spirits – we set a target on Friday night to knock on 20,000 doors, and we are well over half way.
"The reception is genuinely really good. You get a bit of apathy, as you always do, but we don't think our vote is collapsing – far from it."
Bookmakers still have Labour as the clear favourite to win the by-election, with William Hill quoting a Labour victory at 2/5 and Ladbrokes quoting the party at 4/11.
But the biggest move in the odds has been towards the Conservatives, who came fourth in 2005 and had just 7 per cent support in the most recent opinion poll. Their odds have been slashed from 100/1 to 33/1.