Senior Liberal Democrat Danny Alexander faces losing his Highland seat to the SNP at the next general election, according to a poll.
The Chief Secretary to the Treasury has the support of just 16% of constituents, compared with 32% for Alex Salmond’s party and 25% for Labour, the ICM poll suggests.
The prediction was revealed by Lib Dem peer Lord Oakeshott on the day he quit the party during a damaging row about Nick Clegg’s leadership and the disastrous European election result.
It follows other snapshot polls in key Lib Dem areas - including Mr Clegg’s Sheffield Hallam constituency - which could be lost at the next general election.
The Lib Dems dismissed the latest poll on the Inverness, Nairn, Badenoch and Strathspey constituency as “deeply flawed”.
But SNP MP Angus Robertson, who holds the neighbouring Moray seat, said: “The European election results gave us an idea of how badly the Liberal Democrats are doing as they were swept off the electoral map of Scotland, but for their senior cheerleader in the Tory-led No campaign to be relegated to third place is another humiliation.
“The Lib Dems are tearing themselves apart and this poll will make Danny Alexander wince as support in his own constituency evaporates, with only a slightly higher vote than the Tories in fourth place.”
The prediction is based on responses from 500 people phoned at random in the constituency over the weekend.
Mr Alexander took the seat in the 2010 election with 40% of the vote, compared with 18% for the SNP.
A spokesman for Mr Alexander said: “Recent research has shown that Liberal Democrat MPs get an 11-point lift in such polls when people are specifically asked to think about their own constituency and their MP.”
He said the ICM poll does not bear scrutiny, instead highlighting research by the local Inverness Courier newspaper which suggested Mr Alexander could retain his seat.
“The Courier knows the constituency intimately and is better placed to assess the political mood than a remote polling company using a flawed methodology,” he said.