Veteran Liberal Democrat John Farquhar Munro has backed Alex Salmond for another term as first minister.
He told the BBC the SNP leader was "the best man for the job", but insisted he was not endorsing the SNP.
But Mr Munro said he remained a "strong Lib Dem" and would be out campaigning for the party ahead of the 5 May Scottish election.
He decided to step down from parliament after being first elected MSP for Ross, Skye and Inverness West in 1999.
The Liberal Democrats downplayed the remarks, saying that "in the race between Labour leader Iain Gray and Alex Salmond, John Faquhar Munro would choose Alex Salmond."
Mr Munro's comments came after the Scottish Liberal Democrats lost their top candidate in Central Scotland, after he criticised the party.
Tavish Scott, leader of the Scottish Lib Dems, responded to Mr Munro's endorsement of Mr Salmond by saying "these things happen".
He added: "John answered a straight question and gave a straight answer, which is given the choice between Mr Gray and Mr Salmond, he'd rather back Mr Salmond.
"John Farquhar has been out campaigning today for the Lib Dems, he said he is going to vote Lib Dem and support Lib Dem candidates across the Highlands and Islands."
The SNP had spent the day of campaigning in the Lib Dems' Highland heartland, where they hope to make gains.
Speaking to BBC Scotland, Mr Munro said of Mr Salmond: "I think he's done an excellent job in the last session of parliament and I'm quite happy to support him for a second term.
"I think he's the most appropriate person we've got in the Scottish Parliament at the present time to undertake that job."
But Mr Munro insisted: "I don't do this because of his politics, I do this because of his personality, his ability and his acumen.
"I'm still a strong supporter of the Lib Dems and always have been - I will continue to be that."
Mr Munro said he, "never have and never will" back the SNP, and said of the Scottish Liberal Democrat leader: "Tavish Scott is an excellent leader of the party and I think that's his role in the next session of parliament and I still think that Alex Salmond is the best man for the job."
Asked about what his party colleagues might think, Mr Munro said: "They've considered me a maverick in the past and I suppose nothing has changed."
Mr Munro declared his backing for Mr Salmond a "message of support".
Mr Munro was one of a number of Lib Dems to have openly supported the staging of an independence referendum in the last parliament, against the position of the party leadership.
Mr Salmond said: "John Farquhar Munro is hugely respected and has an outstanding record as a selfless champion of his constituency, the needs of the Highlands and Scotland's interests.
"I greatly value John's opinion. This is a personal endorsement but he speaks for many across the Highlands of Scotland."
The Liberal Democrat election campaign has already suffered a blow after Hugh O'Donnell, the leading candidate in the party's Central Scotland list, quit to stand as an independent.
He claimed the party's founding principles had been "subsumed" by a desire for position and power.
And in another development, the Scottish Lib Dems have been left without a candidate in South Lanarkshire constituency of Clydesdale, after candidate John Paton-Day failed to get his papers in on time.
However, he is a candidate on the regional list.