Liberal Democrat and Conservative leaders have launched vicious attacks on each other as both parties claim they are the only alternative to the SNP in North East Fife.
Willie Rennie accused Ruth Davidson of putting “party before country” after the Scottish Tory boss targeted would-be Lib Dem voters while campaigning in the constituency at the weekend.
Bookmakers have the SNP as 1/4 favourites to come from fourth place and claim the seat, with the Liberals at 3/1 and the Conservatives 25/1 to provide a replacement for the retired Sir Menzies Campbell.
However, the analytical website Electoral Calculus predicts the Tories have a narrow advantage over their former coalition partners, with an 8% chance of winning rather than 7%.
Mr Rennie said: “The Conservatives in Scotland are getting in the way of our battles to stop the SNP in the 11 Westminster seats we hold in Scotland.
“Just the other day the Scottish Conservative leader was visiting North East Fife claiming they can win. It’s a seat the bookies say is a close race between the Liberal Democrats and the SNP.
“The Tories are also-rans. The only result of their reckless actions would be to divide the non-SNP vote and let the SNP win.
“I don’t doubt the Conservatives’ loyalty to the United Kingdom but their actions show they are putting their party before their country.”
Mr Rennie claimed that any traditional Conservatives are backing his party locally through tactical voting.
Ms Davidson hit back, saying: “Everybody is clear that the Scottish Conservatives are the most pro-union party and I stand by my record in the referendum. Independent individual seat polling shows a number of sitting Lib Dems are already on third place and out of the race.
“People should vote for what they believe in at this election and not have their head turned by desperate parties peddling half-truths to try and save their own skins.”
The SNP candidate for North East Fife, Stephen Gethins, said: “The Lib Dems have been in coalition with the Tories for five years, and campaigned arm in arm with them in the referendum they fully deserve to pay the price for imposing unfair Tory policies and cuts on Scotland.”