A new row has broken out over Scottish Labour's demand for an early referendum on independence.
Labour MSPs have said they could not guarantee support for a referendum Bill when ministers bring it in 2010.
Following a group meeting, the party insisted it had never promised a "blank cheque" to the Nationalists.
The SNP said it was the latest in a "ludicrous series of U-turns" since Scots Labour leader Wendy Alexander urged ministers to speed up plans.
Following the Labour meeting at Holyrood, party group convener Duncan McNeil said there was "no principal objection" to a referendum.
But he added: "The Scottish National Party have been given an opportunity to bring the referendum here last week.
"They refused to do that. We will not give up our right to scrutinise that bill."
The row started after Ms Alexander called on the Scottish Government to "bring on" a referendum on independence but ministers have refused to speed up their current timetable.
Prime Minister Gordon Brown has pledged to do "whatever is necessary" to preserve the United Kingdom - although he has given his backing to Ms Alexander, describing her as an "excellent leader" of Labour in Scotland.
Scottish deputy first minister Nicola Sturgeon said: "Wendy Alexander must accept responsibility for this ludicrous series of U-turns that have left Labour turned inside out.
"'Bring it on' has been brought down, and Labour must now be very close to bringing Wendy Alexander down as their Holyrood leader."
David McLetchie MSP, Scottish Conservative chief whip, said: "Incredibly, 10 days after Wendy Alexander set the ball rolling by hollering 'bring it on', the situation is as muddled and chaotic as ever.
"Wendy is saying one thing. Duncan McNeil is quite obviously saying another. Gordon Brown doesn't want to know. And Des Browne doesn't seem to care.
"What an absolute mess. Few people will be sorry to see the Labour Party ripping itself to shreds but the more serious point is that Labour is endangering the future of the Union by its chronic incompetence."
He added that the uncertainty must end and called for the party to set out a clear position.
Leader of the Liberal Democrats in Scotland Nicol Stephen said: "The Labour Party's behaviour over the last week has been bizarre and bewildering.
"Wendy Alexander's flip-flop on the referendum and the consequent failure of the prime minister to support her has plunged her party into chaos.
"The Labour Party has made a seventh attempt to redefine the conditions in which they would support a referendum.
"Anyone trying to keep pace with Labour's ever-changing position would be driven to dizziness. No wonder nobody knows what Labour stand for anymore."