By politics.co.uk staff
Ed Miliband's leadership faces a new test today, as Labour defends a substantial majority in Inverclyde against a resurgent Scottish Nationalist party (SNP).
Normally, the 14,416 majority would seem insurmountable, but with the SNP claiming extraordinary gains in the May elections and riding a wave of expectation since then Labour strategists are concerned about the result.
With jobs and pensions standing out as the key areas of debate, Labour sent former deputy prime minister John Prescott, who has fashioned himself into a campaigning machine since leaving the Commons, to the constituency.
First minister Alex Salmond made his pitch to voters, while Scottish Conservative leader Annabel Goldie and Scottish Liberal Democrat MEP George Lyon have also campaigned in recent days.
The by-election was triggered by the death of popular Labour MP David Cairns, who died aged just 44 after complications of acute pancreatitis last May.
Turnout in the constituency at the 2010 general election was 63.48%.