THE SNP’s longest serving MP has said there will not be a second independence referendum before the next Scottish election.

Instead, Peter Wishart said his party should seek a fresh mandate for one at the 2021 poll.

Mr Wishart, who held his Perth & North Perthshire seat in June by just 21 votes, admitted voters were “weary of constitutional change” at the General Election.

The SNP lost a third of its MPs and half-a-million votes in the election, its worst electoral reverse in almost 40 years.

Writing in the National newspaper, Mr Wishart also conceded the party needed a "new blueprint" for independence which addressed economic issues, including currency.

He said there was “impatience” among SNP members for another referendum, but warned: “Timing is everything and we must seek the optimal time for success, carefully assessing opportunity against risk.”

There must also be an “unquestionable mandate” to overcome objections from a UK government, he said, despite Nicola Sturgeon claiming she already had a “cast-iron mandate”.

He said the impact of Brexit would be a central factor in the next independence campaign, but the SNP should not rush to rejoin the EU after independence, but take a "graduated approach", as many Yes voters remain wary of the EU.

He said: “This means contesting the next Scottish election with a clear commitment to revisit our constitutional future with a reference to allow Scotland to consider its position when Brexit finally concludes.

“With transitional arrangements in place, it is likely that the full impact of Brexit will start to become apparent just as we start to contest the 2021 election.

“We therefore have to seek a renewed mandate in 2021 and have the courage of our convictions to fight the next Scottish election on securing a renewed referendum mandate."

The Tories said the SNP position on a second referendum was now utterly confused.

In March, when Nicola Sturgeon called a second referendum, she said it should be between late 2018 and early 2019, once the terms of Brexit were known.

However after June’s election losses, she kicked a decision on timing down the road, saying she would tell MSPs of the new timescale in autumn 2018.

But in an interview with the New Statesman last week, the First Minister said SNP ministers now didn’t know “whether we want to do it and what timescale we want to do it”.

The timing of a second referendum is likely to be at the forefront of delegates’ minds at the SNP conference in Glasgow next month.

Mr Wishart said a new blueprint for independence, an “Independence 2.0”, should replace the SNP Government White Paper published in November 2013.

He said: “Scotland in 2017 is an altogether different country from the time of the white paper.

“Independence 2.0 must be positive and realistic, with a strong powerful vision of what we want to contribute internationally predicated on the best inclusive, social democratic traditions of our nation.

“We need to demonstrate what we can achieve with the full powers of self Government.”

Mr Wishart said the Yes movement “urgently requires reassurance” and “we need to offer a new prospectus that will re-motivate and inspire”.

He said: “These are people looking for a new way forward for their constitutional ambitions and who are looking to the Scottish National Party to signpost the way to that destination.

“We also now know that this is a fragile constituency that can not be taken for granted.

"We lost a third of our Westminster MPs just as much because independence supporters decided to stay at home, uninspired by what they saw as an agenda that did not meet their constitutional ambitions.”

He said the SNP needed “a credible post-Brexit vision for an independent Scotland”, adding: “We also need to be sensitive to the many people in Scotland (including the many SNP supporters) who remain suspicious of the whole EU project.

“We need a graduated approach, starting with institutions we can apply to join on day one of our independence.

"We should say that we would seek immediate entry to the EEA and EFTA while starting discussions about a return to the European Union.

“We should also say that our membership of any European multilateral institution will be kept under review in any ascent up that stairway to full European Union membership.”

He said Independence 2.0 should address the currency issue which hamstrung the Yes campaign in 2014: “So much time and energy was spent addressing currency in the last referendum that we must never again allow the Unionists to hold the whip hand on what we may or may not be ‘allowed’ as an independent nation.”

Tory MSP Murdo Fraser said: “Pete Wishart’s comments will only add to the confusion over what the SNP’s policy is on a referendum.

“And the trouble is that, while the SNP continues to dither, investment decisions will be put off and more uncertainty will be cast over Scotland’s future.

“Nicola Sturgeon has shown a total failure of leadership on this matter over the summer.

“She now has a responsibility to take control and make it clear to her party that a referendum is off the table for good.”