BY-ELECTIONS have a history of producing dramatic results which can shake governments and create major political aftershocks. Labour's loss of the previously safe Crewe & Nantwich seat in Cheshire two months ago was seen as a portent of doom for Gordon Brown's government.
More recently, Alex Salmond predicted an "earthquake" when voters go to the polls next week in Glasgow East – one of Labour's safest seats in Scotland.
The SNP has had its share of by-election triumphs over the years, but there are signs the man
who led the SNP to victory in last year's Holyrood elections could be in for a disappointment this time.
Insiders in all parties, including the SNP, are saying privately that the Nationalists have "over-hyped" their chances next Thursday. The most likely result, they believe, is that Labour will hang on, but with a severely reduced majority.
One senior opposition politician says: "Alex Salmond and the SNP have allowed themselves to be talked up to the extent that if Labour now manages to get back with a majority down from 13,500 to 1500 it will look like some kind of triumph."
An SNP source admits Labour is likely to hold the seat: "The momentum is not there. The party has never worked the area in the past. Labour will probably hang on – but only just. That would be good for Brown in the short term, but the long-term problems will still be there."
Labour's campaign got off to a farcical start when their favoured candidate failed to turn up for the selection meeting. He later told party bosses he was not willing to stand after newspapers began to rake up ten-year-old allegations of housing benefit fraud, over which he was exonerated. Glasgow council leader Steven Purcell and Labour MSP Frank McAveety were supposedly then approached without success before the party's Holyrood health spokeswoman Margaret Curran agreed to step into the breach and become the candidate.
She has to explain how she will serve both as an MP and MSP – but the SNP is in no position to object since Mr Salmond already combines those roles.
Opposition parties are bemused that Labour called the by-election – caused by the resignation on health grounds of veteran MP David Marshall – before making sure they had a candidate in place.
The general view, however, is the party has ended up, by a circuitous route, with the best candidate it could have got.
Ms Curran's Baillieston seat in the Scottish Parliament makes up a large part of the Glasgow East Westminster constituency.
Although the SNP is making much of the fact she lives outside the constituency, she is said to be popular in the area.
Early talk of the Nationalists choosing former MSP Duncan Hamilton or Andrew Wilson as its candidate soon evaporated. Instead, the party settled on John Mason, a Glasgow councillor for ten years and leader of the 22-strong SNP group on the council, who has lived in the city's east end for almost 20 years.
The SNP wants to capitalise on discontent and disillusionment and make the by-election about sending a message to Gordon Brown and Labour at Westminster.
Labour, on the other hand, hopes to persuade voters to see it as their chance to choose someone to stand up for the interests of the area.
Glasgow has given the SNP two of their most significant by-election victories in the past – Margo MacDonald's 1973 triumph in Govan and her husband Jim Sillars' win in the same seat in 1988.
Ms MacDonald does not forecast a repeat in Glasgow East, though. She said: "I don't think there has been enough flair or imagination or excitement."
She said she is impressed with Mr Mason as the SNP's standard-bearer, despite Labour branding him a "hardline Nationalist". "Hardline means you will fight for every last halfpenny that should be coming to Scotland. The SNP have been far too timid. If they gave that candidate his head he would know what he was doing and he would be able to argue the case," she said.
Last year's Holyrood election result and the continuing popularity of the SNP minority government should give the Nationalists a good chance, even in traditionally solid Labour territory.
A defeat for Labour in Glasgow East would undoubtedly be a serious blow to Gordon Brow, but canvassers claim some voters promising to stick with the party say they are fed up with all the criticism being heaped on the PM.
A defeat for the SNP could also prove an unwelcome setback for Mr Salmond, with one Nationalist insider saying the First Minister has "blotted his copybook" by being too gung-ho about the by-election prospects.
The SNP urgently needs to manage expectations – not only among the public, but also among the hundreds of activists it has brought in from all over the country to help in the campaign. They will go home disappointed if their efforts end in defeat.
SNP 'EARTHQUAKES' OVER THE YEARSMotherwell, 1945: Scottish Nationalist Robert McIntyre takes the former Labour seat but loses it at the general election three months later.
West Lothian, 1962: SNP candidate Billy Wolfe causes a stir with a surprise second place as Tam Dalyell is elected for the first time.
Hamilton, 1967: The SNP's Winnie Ewing wins the former Labour stronghold with a 37.9 per cent swing – the Nationalists' first major breakthrough.
Govan, 1973: "Blonde bombshell" Margo MacDonald is elected on a 26.7 per cent swing from Labour to the SNP. The party goes on to win 11 seats in October 1974.
Govan, 1988: Scottish Nationalist Jim Sillars repeats his wife's victory 15 years earlier with 33.1 per cent swing from Labour.
Perth & Kinross, 1995: Roseanna Cunningham wins the former Tory safe seat after the death of Sir Nicholas Fairbairn.
Livingston, 2005: The SNP fails to win Robin Cook's old seat from Labour, despite a swing of over ten per cent.
Dunfermline & West Fife 2006: The Lib Dems edge out the SNP to snatch the seat with an 1800 majority.
The full article contains 1021 words and appears in Edinburgh Evening News newspaper.