Nicola Sturgeon has admitted there may not be a second independence referendum in the current parliament, forcing her to try to secure one at the next Holyrood election.

The First Minister said she may not be able to overcome the UK Government’s rigid refusal to grant Holyrood the power to hold another vote before 2021.

Ruling out an unofficial Catalan-style vote, she suggested the best option could be to complain vigorously about the UK’s action and seek a new mandate from the voters.

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However polls suggest the SNP will lose seats at the next Holyrood election, with Unionist parties in the majority, and so there would be no chance of a referendum after 2021 either.

The statement is likely to dismay many in the SNP, including MPs like Angus Brendan MacNeil, who called for a swift second vote at the SNP conference in October.

Ms Sturgeon’s admission, made at a weekend meeting of the Women for Independence group, came after repeated delays to her long-awaited “precise timescale” on Indyref2.

A new poll also gave a 20-point lead to No campaign.

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MSPs voted 69-59 to request referendum powers from Westminster in March 2017, but Mrs May simply refused.

After the SNP lost a third of its MPs at the 2017 general election, most to to the Tories, Ms Sturgeon said she would update Holyrood this October on her referendum timetable.

However this was delayed because of the turmoil over Brexit, with Ms Sturgeon saying she needed more clarity before making a call on timing.

Even after Mrs May published her 585-page draft withdrawal agreement last week, Ms Sturgeon said she needed to wait for “the dust to settle”.

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At the weekend, Ms Sturgeon said: “I don’t have an easy answer to this.

”We may get into a situation where the UK government says ‘No, we’re not going to agree the Section 30 Order [transferring referendum powers to Holyrood]’.

“And I think if that happens, we need to rise above that, we need to make a case of how unreasonable that is.

“And ultimately, if the only way through that is to take that to an election, and ask the people of Scotland to use an election to say ‘No, we will have absolutely our right to choose, I think maybe that’s what that will take.”

One option for the SNP leader would be write an explicit commitment to holding a second referendum into her party’s manifesto for 2021, perhaps with the Scottish Greens using the same wording, so their combined total of MSPs would have the same mandate.

At the last Holyrood election, the SNP and Greens made different pledges on the issue, and even though they constitute a pro-independence majority, they have a muddled mandate.

Ms Sturgeon's official spokesman denied she believed a Section 30 order was now unlikely before 2021, but added: "This will be an issue at the next election if it has not been resolved before then."

Scottish LibDem leader Willie Rennie said: "Rather than admit this to her own side in secret, Nicola Sturgeon ought to stand up in Parliament and tell the whole country that independence is off the table. 

"We’ve seen the damage caused by Brexit, we don’t need more chaos and uncertainty with independence.”

A new Survation poll for the anti-independence Scotland in Union group this week found 60% of Scots would vote to ‘Remain’ in the UK, and only 40% would vote to ‘Leave’, if the same terminology as the EU referendum was applied to independence.

However this feel to 52-48 for Remain if there was a No Deal Brexit.

The SNP were at 39% on Westminster voting intention, compared to 26% for the Scottish Tories, 24% for Scottish Labour, and 8% for the Scottish LibDems.

SNP Depute Leader Keith Brown said people continued “to put their trust in the SNP to stand up for Scotland” while the Tories were “consumed by complete and utter chaos of Brexit”.

He said: “It’s clear a bad Brexit will draw more and more people towards the opportunities of independence as Scotland’s interests continue to be sidelined by Westminster.

“It seems this poll was commissioned by our opponents to land a political blow on the SNP, whereas it’s had the exact opposite effect. These figures make extremely encouraging reading for the independence movement while leaving the Tory and Labour parties extremely downhearted. It’s a spectacular boomerang attack.”

Tory MSP Adam Tomkins said: Nicola Sturgeon has thrown everything at breaking up Britain over the past four years. Yet support for independence seems to be on the wane as a result.

“The First Minister should heed the advice of this research and take the threat of another independence referendum off the table altogether.”

Labour MSP Neil Findlay said: “It is clear that the people of Scotland are resoundingly rejecting Nicola Sturgeon’s plans for further instability and chaos.”

Scotland in Union chief executive Pamela Nash said: “This bombshell poll shows that a huge majority of Scots want to remain in the UK and are turned off by Nicola Sturgeon’s desperate attempts to use Brexit to break up Britain.

“This poll reveals how the SNP’s tactics have backfired, and shows that people in Scotland would vote to remain in the UK with or without a Brexit deal in place.”