Former Liberal Democrat leader Charles Kennedy has told the BBC it is "highly unlikely" that he will seek to succeed Sir Menzies Campbell in the job.
Mr Kennedy, who said he was "gratified" by messages of support, did not flatly rule out running, but added that it was not part of his "game plan".
Chris Huhne and Nick Clegg are the early frontrunners for the job.
Mr Kennedy, who quit as Lib Dem leader last year, said "thousands" of possible supporters had been in touch.
'Never say never'
Asked on BBC Two's The Daily Politics whether he would bid to return to the top job, he replied: "I think it's highly unlikely, to be honest."
He added: "You should never say never in politics, but as close to never as you can get."
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Mr Kennedy, who was Lib Dem leader from 1999 to 2006, when he resigned following the revelation that he had a drink problem, said he had received messages of support from "all over the place" since Sir Menzies resigned on Monday.
He wanted to reply to them first "out of courtesy".
Mr Kennedy insisted he had no knowledge as to whether Sir Menzies had "a knife in his back or not", and said he believed the situation would be sorted out quickly.
He added: "After the initial adrenalin that surrounds a major event like this, things do quite rapidly calm down.
"With 24-hour news... the story moves on with the media."
'Smoke of battle'
Mr Kennedy also said: "I didn't think there'd be a leadership vacancy in the Lib Dems in this parliament, and certainly not to contest one, I'm quite happy with the role I've got."
He later told BBC Radio 4's World at One he was likely to "remain above the smoke of battle", by not backing any leadership contender.
Mr Kennedy added: "At the moment, the party is facing clearly a bit of a squeeze between Labour and the Conservatives."
The winner of the contest had to "get a distinctive voice heard", he said.
Mr Huhne, the party's environment spokesman, is expected to announce his candidacy on Wednesday.
Mr Clegg, the home affairs spokesman, and Steve Webb, who is writing the party's manifesto, have both said they are considering their position.
Treasury spokesman and acting leader Vince Cable has ruled himself out of the contest, as have elections co-ordinator Edward Davey, transport spokeswoman Susan Kramer and party president Simon Hughes.