Former Liberal Democrat leader Charles Kennedy has made his first major public appearance since quitting over his alcohol problem.
Charles Kennedy stepped out on the campaign trail in Dunfermline
He was one several big-name politicians campaigning for their candidates in the Dunfermline and West Fife by-election.
Tory leader David Cameron canvassed in the town on Thursday while Gordon Brown hit the campaign trail for Labour. SNP leader Alex Salmond was also present.
Nine candidates are contesting the by-election on 9 February.
The by-election has been viewed as a crucial test for all of the main parties.
The Lib Dems overtook the SNP to come second in the constituency in last May's general election.
Activists hope Mr Kennedy's personal popularity will boost the campaign of Willie Rennie, who insisted the contest is a two-horse race with Labour's candidate, the MEP Catherine Stihler.
Mr Kennedy accompanied Mr Rennie on a walkabout in Dunfermline city centre.
The former party leader said: "I know Willie well and I know that he will be an excellent MP. He is a very strong local choice and he will stand up and fight for local people."
Mr Rennie said the visit by Mr Kennedy had provided a massive boost to the local Liberal Democrat campaign.
Labour are defending a majority over the Liberal Democrats of more than 11,500 and tolls on the Forth Road Bridge, as well as the future of the bridge, are issues that have loomed large.
A day after Labour launched its campaign, highlighting its economic record, printer firm Lexmark announced the closure of its factory in the constituency with the loss of 700 jobs.
Chancellor and Kirkcaldy and Cowdenbeath MP Gordon Brown toured a subsea cable manufacturing plant in Rosyth with Labour candidate Catherine Stihler, where 40 new jobs are planned.
David Cameron has been campaigning in Dunfermline
He argued that Fife now has a much more diverse economy than in the era when it relied on the mining industry and defence jobs.
Mr Brown also discussed the controversial issue of Forth Road Bride tolls.
At the start of the campaign the chancellor said plans for an increase of up to 400% had been abandoned, a claim which was disputed by the Scottish Executive whose ministers have yet to decide on the application.
In Dunfermline on Thursday, Mr Brown denied meddling in matters beyond his remit.
"I was reflecting the views that [First Minister] Jack McConnell himself has expressed - that the £4 toll is dead in the water," he said.
The Tories, whose candidate is Carrie Ruxton, hope to improve on their fourth place position.
Mr Cameron and Ms Ruxton, who runs a small nutritionist's business in the town, met locals on the high street as they canvassed for votes, followed by a huge media scrum.
One onlooker heckled the Tory leader and his candidate, shouting: "You shut down the mines."
Mr Cameron insisted that Ms Ruxton had a chance of winning the by-election despite trailing there in previous polls.
He said: "Carrie's fighting very hard, she runs her own business, she's a mum, she lives locally and I think she'd do a great job for the area."
Mr Cameron declined to say what he thought the Forth Road Bridge toll should be, but said his party policy was to build a new road bridge.
The cost of crossing the Forth Road Bridge has been on the agenda
SNP leader Alex Salmond, who was in the constituency with candidate Douglas Chapman, claimed the Lib Dems had "lost their way" and dismissed the Tories as "rank outsiders".
"All indications", Mr Salmond claimed, were that the contest would be a close fight between his party and Labour.
Scottish Socialist Party candidate John McAllion, the former Dundee Labour MP and MSP, campaigned with the party's drugs spokeswoman Rosemary Byrne MSP.
The pair visited Dunfermline Drugs Forum to get a clearer picture of the drugs problem in and around the town.
UKIP chairman David Campbell Bannerman was also in the constituency, lending his support to candidate Ian Borland.
Mr Campbell Bannerman visited Dunfermline's Carnegie Hall, where he said his great-uncle Henry Campbell Bannerman made his first speech to become a Liberal MP, before serving as prime minister from 1905-08.
Tom Minogue, who is standing for the Abolish Forth Bridge Tolls Party, promised to put pressure on Gordon Brown to live up to his 1985 promise to abolish the "excessive and unreasonable" tolls if elected.