As voters go the polls, officials and senior figures in the SNP and Labour believe the gap between the parties is very small Alex Salmond is close to landing another wounding blow on the Labour party as voters head to the polling stations in the Inverclyde byelection. Officials and senior figures in both the Scottish National party and Labour believe that the battle to win Inverclyde , a once rock-solid Labour constituency west of Glasgow, has gone to the wire with the SNP on the brink of snatching the seat. The byelection was called after the sudden death of its popular Labour MP and former minister David Cairns, 44, shortly after the SNP’s landslide victory in May’s Scottish parliament elections . Despite holding the Westminster seat and its near equivalents for some 80 years, Labour has been struggling to defend its 14,416 vote majority against the SNP, which came within 500 votes of winning the equivalent Holyrood seat in May. Labour admits the result could come down to a few hundred votes, with many predicting a low turnout: the party has pressed its activists into another, late surge of campaigning and drafted in Lord Prescott on the day before polling. Salmond has visited the seat five times during the short campaign. “I think this is earthquake proportions if we win this seat,” he told BBC Scotland on Wednesday. “I think that the political impact of a victory for the SNP in Inverclyde would be absolutely huge.” SNP officials said on Thursday the difference between the two parties was “very tight”. One said: “We’ve closed the gap an awful long way, down to a thousand or a couple of hundred, but it has been very hard to tell over the last couple of days, incredibly difficult.” Anne McLaughlin, the SNP candidate hoping to become the party’s seventh MP at Westminster, accompanied her mother, Betty, to a polling station at a local sailing club on Thursday morning. Raised in the area, McLaughlin no longer lives in the constituency. In her election day address to voters, McLaughlin took inspiration from Winnie Ewing’s famous byelection victory for the SNP in Hamilton in 1967, claiming that and other byelection upsets shocked the UK government into making concessions to Scotland. She said: “I promise you that if elected to serve as MP, I will defend Inverclyde’s interests and promote our future with every bone in my body. “Labour can’t and won’t fight back and take on the Tories and their cuts at Westminster. They stopped listening a long time ago.” Labour’s candidate, Iain McKenzie, the local council leader, cast his vote at a scout hall in Greenock. Stopping far short of predicting a victory, he said: “This is a beautiful sunny day in Inverclyde and there’s a great feeling in the air.” He added: “I am proud to be the Labour candidate and I am proud to be the local candidate and I will be working every minute of today until polls close to earn the trust of my friends and neighbours in Inverclyde.” Sophie Bridger, for the Liberal Democrats, was out in the constituency urging party supporters to vote. The Scottish Lib Dem leader, Willie Rennie, who won a shock byelection victory in Dunfermline and West Fife byelection in 2006, a Westminster seat in Gordon Brown’s backyard, said turnout on Thursday would be crucial. “When I won Dunfermline and West Fife, I didn’t know I would, so I think a lot of these things are very fluid, especially with low turnouts – which I suspect, so soon after the Holyrood election, this will be. It’s quite difficult to tell,” he said. General election 2010 result: Inverclyde David Cairns (Labour) 20,933 votes (56.0%) Innes Nelson (SNP) 6,577 votes (17.5%) Simon Hutton (Liberal Democrat) 5,007 votes (13.3%) David Wilson (Conservative) 4,502 votes (12%) Peter Campbell (Ukip) 433 votes (1.2%) Majority: 14,416 (38.4%) Turnout: 37,512 (63.4%) Inverclyde byelection candidates: Labour: Iain McKenzie SNP: Anne McLaughlin Conservative: David Wilson Liberal Democrats: Sophie Bridger Ukip: Mitch Sorbie Scottish politics Scotland Labour Scottish National Party (SNP) Alex Salmond Byelections Severin Carrell guardian.co.uk