Scottish Liberal Democrat leader Tavish Scott has quit the post, after his party's disastrous night at the polls in the Scottish Parliament election.
The number of Lib Dem MSPs dropped from 16 to five, as the SNP cashed in on a collapse in the party's vote.
Mr Scott is the second party leader to go, after Labour's Iain Gray made a similar decision on Friday.
The UK government coalition, Mr Scott conceded, had damaged his party's Holyrood election chances.
The Lib Dems lost 25 deposits after failing to win 5% of the vote in some areas.
The party's only new face at Holyrood, Willie Rennie, could emerge as a likely front-runner to take over as leader.
Announcing his departure with immediate effect, Mr Scott 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."
Mr Scott, who served as a minister in the last Labour-Lib Dem Scottish government, is to stay on as MSP for Shetland.
Key Lib Dems failed to win seats on election night, including finance spokesman Jeremy Purvis, Margaret Smith, the education spokeswoman, and Mike Rumbles, the chief whip at Holyrood during the last parliament.
Former cabinet minister Ross Finnie also failed to be re-elected in the West of Scotland list seat, while another party veteran, Mike Pringle, lost out in Edinburgh Southern, with the Nationalists claiming victory.
Mr Scott was one of only two Liberal Democrats to retain a constituency seat, alongside his Orkney neighbour, Liam MacArthur.
The remainder of Holyrood's Lib Dem MSP complement has come from wins in the regional list vote.
Mr Rennie, who was elected on the Mid-Scotland and Fife list, scored a major victory for his party in 2006 when the Liberal Democrats won the safe Labour Westminster seat of Dunfermline and West Fife, in a by-election.
After failing to hold the seat at the last UK election, Mr Rennie went on to work as an advisor in the Scotland Office.
The other Lib Dems making a return to Holyrood are Alison McInness, on the North East list, and Jim Hume in the South of Scotland.
Reacting to Mr Scott's decision, Mr Gray, said: "Tavish Scott has served his party energetically, and I am sure he will continue to serve his constituents diligently and effectively. I wish him well for the future."
SNP leader Alex Salmond, added: "I have great respect for Tavish Scott, a distinguished parliamentarian with a significant contribution to continue making, and he carries my very best wishes for the future."
Annabel Goldie, leader of the Scottish Conservatives, said: "Tavish has played an important role in the Scottish Parliament as a former minister and as leader of his party. He has always conducted himself with courtesy and dignity. I wish him well for the future."