The Constitution Secretary denied suggestions the timetable for a second independence ballot was unrealistic.
However, at the same time as Angus Robertson revealed the possible time for the crunch vote, a former adviser to both Alex Salmond and Nicola Sturgeon cast doubt on whether it could be delivered by then.
Campbell Gunn, who was a special adviser to Mr Salmond and then Ms Sturgeon, said that the “timescale is very difficult”.
Mr Gunn, speaking on BBC Radio Scotland’s Good Morning Scotland programme, said: “We’re now 15, 16 months from when the referendum is likely to be held, we don’t have a section 30 order, it will probably end up in the courts.
“I just don’t see the timescale working for the SNP.”
His comments came after Mr Robertson told the same programme the Scottish Government intends holding the referendum in October of next year – going further on the timing than Ms Sturgeon, who has only said she wants the ballot to be held before the end of 2023.
Ahead of such a vote, the Scottish First Minister launched the first paper in a series of documents from the Scottish Government designed at updating the case for independence.
While she did not say how she planned for a referendum to be held if Westminster continues to refuse to grant permission for such a vote via a section 30 order, the SNP leader promised a “significant” announcement on this soon.
Mr Robertson, speaking on Wednesday, said: “The First Minister made clear yesterday she intends to make an announcement to the Scottish Parliament in the forthcoming weeks about the route map to the referendum which we intend to hold next October.”
While the UK Government granted a section 30 order prior to the 2014 referendum, allowing a legally-binding vote to be held, Boris Johnson has been clear he will not so the same this time round.
This resulted in the Scottish Constitution Secretary accusing him of “democracy denial” as he argued such an order – which would temporarily transfer powers to Holyrood to allow a referendum to take place – was the “gold standard”.
Mr Robertson insisted: “I see no reason for the UK Government to deny a section 30 order.
“This is the procedure that was agreed in the run-up to the 2014 independence referendum, the gold standard of holding a recognised, agreed, constitutional referendum.”
With the Prime Minister refusing to consider this, Mr Robertson criticised “somebody not elected in Scotland, representing a government that has not been returned in Scotland since 1955, telling the people of Scotland what they can and can’t do”.
He added: “We’re in the territory of democracy denial when I hear things like that.”
The SNP won the 2021 Holyrood election after making a promise to hold another referendum once the Covid crisis had abated in its manifesto.
“Surely all of us involved in politics agree that when the people vote for something to happen in this country, it is what should happen,” Mr Robertson said.
He refused to comment on what could happen if the UK continues to refuse to grant an order, saying only: “I’m not going to get into speculation of what happens a number of steps down the road, we still have the opportunity to secure a section 30 order.
“Scottish politics has a long history of UK governments going ‘no, no, no, yes’. That is what happened in the run-up to the referendum in 2014 and I still think we should work on the basis of the gold standard of democracy.”
He also denied suggestions the Scottish Government’s timetable for a second referendum was unrealistic.
Mr Robertson stated: “I am fully content with the prospectus beginning to be rolled out, with the announcements that will follow on the route map, about how that is going to be achieved, that we have a perfectly adequate window of opportunity both for legislation to be passed, for the opportunity for the people to scrutinise the prospectus the Scottish Government will publish and also hold opponents to account.”
Scottish Conservative chairman Craig Hoy MSP accused the SNP of “ramping up their push for another divisive referendum”.
Mr Hoy said: “This reckless push for another referendum will damage Scotland when all the focus should be on Covid recovery and the global cost-of-living crisis.
“The SNP are distracted by their obsession with independence once again. They’re focusing on the wrong priorities and setting back Scotland’s economy and public services as a result.”
He went on to state it was “a shameful dereliction of duty by the SNP government to focus on holding a referendum that the vast majority of Scottish people don’t want”.
Sarah Boyack, Labour’s constitution spokeswoman at Holyrood, claimed talk of a referendum next October was “nothing more than pie in the sky posturing from Angus Robertson”.
Ms Boyack said: “Thousands of Scots are facing the choice between heating and eating, and the best that this SNP government can do is pluck dates out of a hat for another divisive referendum.”