There is also speculation that SNP leaders may be concerned by opinion polls which show Scots evenly split on independence.
Westminster SNP leader Ian Blackford hinted that the war in Ukraine could push the date for a second vote beyond next year.
He said: “We have got to be respectful of the situation that we are in.
“I want that referendum to take place in a timely manner.
“I want us to be able to execute the mandate that we have.
“To those that are expressing a desire for us to get on with our job, of course, we will do so, but we have to be mindful of where we are.
“We have to play the ball where it lies just now and the only thing that I’m focusing on today is Ukraine.”
Former SNP Cabinet Secretary Kenny MacAskill blasted Mr Blackford over the climbdown.
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“The war brings into sharp focus why independence is necessary for Scotland.
“The risk of an escalation sees Scotland unable to remove weapons of mass destruction from its shores.
“The humanitarian crisis that’s unfolding sees Scotland impotent to play its part in addressing the escalating refugee crisis.
“And finally the economic fallout from the conflict will see the cost of living crisis morph and increase the poverty many Scots are facing.
“Just as the powers of an independent nation are required to address the consequences of Covid, they’re also vital for Scotland in the world created by the invasion of Ukraine.”