A SENIOR polling expert has told the SNP to launch a fresh independence campaign – or risk seeing hopes for a Yes vote fade.

Professor John Curtice issued a warning to the party after new polling found 48% of Scots support independence while 52% are opposed, once undecided voters were removed.

The Panelbase research, commissioned by the Sunday Times, recorded a four point dip in backing for Yes since the last survey in April.

Just under half of respondents (47%) think a second referendum should be held within the next five years. Of those, 19% wanted indyref2 within the next 12 months, down three points since April. A further 35% wanted the vote in the next two to five years, up 2%.

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However, 46% said there should not be another referendum in the next few years, up by one point. Some 22% believe independence will happen within five years, a decrease of 8% since April, but almost a quarter (24%) believe it will happen in five to 10 years’ time, a rise of 4%.

Curtice, of the University of Strathclyde, said the headline figure suggests “a cooling of the independence ardour” since the Holyrood election in May.

He added that the poll indicated “lowered expectations” on Nicola Sturgeon “to press the referendum button any time soon”.

The National: GLASGOW, SCOTLAND - MAY 05:  SNP Leader Nicola Sturgeon returns to her constituency to meet voters on May 5, 2016 in Glasgow,Scotland. Today, dubbed 'Super Thursday', sees the British public vote in countrywide elections to choose members for the

But the polling expert warned the SNP could not risk letting the constitutional debate “be off the boil for long”.

“Rather, the party needs to embark on a campaign to persuade more Scots of the merits of independence,” he commented. “Otherwise, Ms Sturgeon might find herself stuck with a promise to hold a referendum that she has little hope of winning.”

The Sunday Times report also claimed that “many within the SNP leadership circles concede that there will not be another independence referendum” before the next General Election, currently scheduled for May 2024. 

Last week, Michael Russell was appointed as political director at the SNP's independence unit.

READ MORE: Michael Russell set to take on a key role in SNP campaign for independence

The task force was unveiled in January, with depute leader Keith Brown saying it would create policy papers and campaign materials to "fire up" the Yes movement.

First Minister Nicola Sturgeon said she was delighted that a meeting of the SNP’s National ­Executive Committee had app­roved her nomination of Russell for the role.

“He will oversee the development of the party’s independence campaign, as we look ahead to #indyref2 later in this parliament,” she added.

Russell said he was pleased to take on the political direction of the work on independence.

He tweeted: “Look forward to working with the vast range of enthusiastic talent, within & outwith the party, which is committed to a positive, inclusive – & successful – #indyref2 campaign.”

A total of 1287 adults aged 16 and over were interviewed for the Panelbase poll.