The leaders of Scotland's main opposition parties have given their reaction to the overnight results of the Holyrood election.

The SNP's John Swinney, who following heavy losses will come under pressure to keep his job, came out fighting.

"The message from me tonight at the conclusion of this campaign is that the SNP is determined tonight, as it always has been, to release the potential of Scotland and to make sure that the people of Scotland run and create a very successful, prosperous and fair country and a country that we can all be proud of," he told supporters.

"The arguments that we set out in this election campaign, arguments that have in no way been challenged by our political opponents, are arguments that we will continue to sustain until we achieve our objective of putting in the driving seat of this country the people of Scotland."

Liberal Democrat leader Jim Wallace, set to keep his place in the coalition executive with Labour, said his hand had been strengthened by the results.

"Over the past four years, the Liberal Democrats have achieved 80 per cent of what we put into our 1999 manifesto and I now think we can do better than that," he said after retaining his Orkney seat.

"The most important thing to do is agree the terms of the partnership agreement and what policies the administration will follow over the next four years."

Conservative chief David McLetchie, a personal victor in Edinburgh Pentlands who also saw his party increase their share of the vote, said the results were a dream come true.

"Ever since I joined the Conservative Party at the age of 16 I have dreamed of the day that I would have the opportunity to make a speech like this," he declared.

"We are on our way back. I am proud to have led this party in our campaign and I am looking forward to leading our party in the next parliament."

Scottish Socialist Party MSP Tommy Sheridan, probably the night's biggest single winner, told cheering supporters in Glasgow: "What's happened tonight in Scotland is that a new political force has been formed - and that force believes that the wealth of Scotland belongs to the people of Scotland."