NICOLA Sturgeon’s short-term plan for another independence referendum is doomed and she should focus instead on winning the next Holyrood election, Alex Salmond’s former spindoctor has said.

Kevin Pringle, who was a senior special adviser to the former First Minister, predicted there would not be a new vote by May 2021 because the UK government would block it.

He also said there was not enough time to hold and win a referendum regardless.

He warned that by talking up “a vote that isn’t taking place” there was a risk the SNP would “blur the focus” on winning another pro-independence majority at Holyrood.

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Mr Pringle, a former head of communications for the SNP, is one of the most respected political brains in Scotland, and his comments are a blow to the First Minister.

Ms Sturgeon last week announced she wanted to hold a new referendum within the next two years in order to give the country a way to avoid the economic damage of Brexit.

Her Government is to introduce a framework bill at Holyrood setting the rules for such a vote, and she has asked MSPs to pass it by the end of the year.

However Ms Sturgeon also admitted the bill alone could not deliver a referendum, and she would need the UK Government to transfer extra powers under a so-called Section 30 order.

Theresa May refused Ms Sturgeon’s first request for a Section 30 order in 2017, and this week her deputy, David Lidington, said another request would also be rebuffed.

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Writing in the Sunday Times, Mr Pringle said: “My forecast is that there won’t be another independence referendum this side of the next Holyrood referendum in May 2021, but that the political meteorology points to a fresh vote being held during the parliament thereafter.

“That would be just shy of the last one, which is a reasonable timescale, given how the Brexit process has transformed the nature of the UK that most Scots backed in 2014.”

He said that, although Mr Sturgeon’s referendum bill “certainly ups the ante”, it did so “on a referendum that isn’t going to happen in the short term”.

Besides the UK Government’s opposition, he said: “Even if circumstances at Westminster changed drastically in the forthcoming months, the business of agreeing, legislating, campaigning and finally holding a referendum would take us beyond the next Holyrood election anyway.”

Instead he said a referendum would depend on the Greens and SNP, elected on a clear mandate, forming a pro-independence majority in 2021.

He said: “[That] seems to me to be the strongest mechanism for ensuring another democratic choice on independence; otherwise it will be a very long time before the issue can come back.

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“The risk is that overdoing referendum process now for a vote that isn’t taking place blurs the focus that there must be on May 2021.

“That is where Sturgeon needs to set the Yes movement’s sights.

“Polls show that a majority for independence isn’t far away, and I believe ‘yes’ will win when the question is next put.”

A new Panelbase poll for the Sunday Times suggested the SNP on course to win 60 MSPs and the Greens seven at the next Holyrood election, a combined majority of five.

The SNP has been asked for comment.