The leader of the Scottish Liberal Democrats has stepped down from his post after a "disastrous" result for the party in the Scottish Parliament elections.
Tavish Scott said his party had been "up against it" since the coalition between the Liberal Democrats and the Conservatives took power in Westminster last year.
The Scottish Liberal Democrats suffered a heavy defeat in the Holyrood election, losing deposits after 25 constituency candidates failed to gain 5% of the vote. The Scottish Parliament will have just five Lib Dem MSPs, with no constituency seats on the mainland. They had 16 MSPs in the previous parliament.
Mr Scott said: "I have just no doubt that since last May we have been up against it because of the formation of a UK government where the Liberal Democrats were seen to be propping up the Conservatives. And that's, I think, in Scotland, a pretty disastrous and toxic mix in politics.
"It's for the party now to decide how to move forward and I think that's best done with a new leader."
In a statement Mr Scott, who was elected leader of the party in August 2008, said he was resigning the leadership with immediate effect.
He said: "Thursday's Scottish general election result was disastrous and I must and do take responsibility for the verdict of the electorate. The party needs a new direction, new thinking and new leadership to win back the trust of the Scottish people. I am honoured to serve as Shetland's MSP in this Parliament."
Former Lib Dem leader Charles Kennedy said: "I am extremely sorry to learn of Tavish's decision to step down. He was handed mission impossible in the Scottish elections, given the current coalition unpopularity. That was always likely to be the case, as some of us warned at the time one year ago.
"Tavish is one of our country's most talented politicians and his response today is characteristically honourable. It deserves to be met by a response at a UK Liberal Democrat level which is similarly honest."
The Liberal Democrat leader, Deputy Prime Minster Nick Clegg, said: "I was very sad to hear of Tavish's decision. He has been an excellent and energetic leader of the Scottish Liberal Democrats at an extremely difficult time, as well as a good friend and colleague."