First Minister Alex Salmond is to publish a white paper proposing a Scottish independence referendum.
Mr Salmond said he would have some convincing to do in Holyrood
The document will be released in about two weeks' time as part of the SNP's plans to mark 100 days in power, it is understood.
But speaking to the BBC, Mr Salmond conceded that the political arithmetic in the Scottish Parliament meant he would have some persuading to do.
Labour, the Tories and the Lib Dems said the move was a waste of time.
Mr Salmond claimed about 50 of the 129 MSPs were in favour of independence.
"I think the political arithmetic in the Edinburgh parliament is such that I've got a bit of work to do before I can persuade that parliament," Mr Salmond said of the move.
It was backed by the Scottish Greens, but the other main parties urged the minority SNP government to focus on devolved issues such as health and education.
Labour MSP George Foulkes said: "The SNP's plans to publish a white paper on independence confirms their arrogance and failure to listen to the overwhelming views of the Scottish public.
"Despite two thirds of Scots voting against independence just months ago, the SNP are hell bent on breaking up Britain."
Scots Tory chief whip David McLetchie said Scotland needed a change of policy, "not a change of passport", adding: "This is a complete waste of everyone's time.
"There is certainly no appetite for the disruption and uncertainty that even the prospect of a referendum would cause."
Nicol Stephen, the Scottish Liberal Democrat leader, said producing the white paper would be a waste of civil service time and taxpayers' money.
"There is nowhere near a majority for independence in the Scottish Parliament," he said.
"Every minute spent on this document is a distraction from more important priorities."
But the pro-independence Scottish Greens welcomed renewed debate on future powers for the Scottish Parliament.
The party's policy convener Patrick Harvie said: "Given the lack of a majority, the challenge for the first minister is to produce a white paper which will provoke real debate across the traditional dividing lines.
"We've just had an election in which pro-independence arguments were stacked up against pro-UK arguments, with each side shouting the other down. What's needed now is a more long-term, thoughtful discussion about Scotland's constitutional future."