NICOLA Sturgeon is facing a conference showdown after six party branches backed plans for a new currency within the first term of an independent Scottish Parliament.

The SNP leadership has not supported a fixed timescale for scrapping sterling, but branches are supporting an alternative plan they hope will be approved at the Edinburgh gathering next month.

However, new polling conducted for Progress Scotland, a research group fronted by former SNP Westminster leader Angus Robertson, found support for keeping sterling in the long term.

Pamela Nash, chief executive of the pro-UK Scotland in Union, said: “The SNP splits are deepening and the row looks set to explode at the party’s conference.

The split is between those who want to put salaries, mortgages and pensions at risk sooner, and those who want to put them at risk a bit later. The SNP should drop this reckless plan, stop playing games with Brexit and take the threat of a divisive and unwanted second independence referendum off the table.”

The Yes campaign fought the 2014 referendum by promising that a currency union with the rest of the UK would be set up after independence.

However, the three main Unionist parties ruled out the policy, which dealt a severe blow to the Yes side’s economic arguments.

Post-referendum, the SNP tasked a Growth Commission to rethink the economic case for independence, including a review of the offering on currency.

The Commission, chaired by former SNP MSP Andrew Wilson, proposed that Scotland would retain the pound for a lengthy transition period after independence.

The plan angered left-wingers who believe an independent Scotland should dump the pound as a priority and use its own currency.

Pressure on the leadership led to a policy shift - a less cautious approach to a new currency - which was revealed in a motion to the Edinburgh conference.

It stated: “Conference believes that it should be the policy of an SNP government in an independent Scotland to establish an independent currency; and agrees that the process and precise timescale for doing so should be subject to robust governance and guided by the six tests recommended by the Sustainable Growth Commission.”

However, critics believe the “six tests” are a way of putting up roadblocks to the creation of a new currency.

A new group, the Campaign for an Independent Currency (CIC), drafted an amendment which explicitly put a timescale on setting up a new currency.

It stated: “Conference believes it should be the policy of an SNP government in an independent Scotland to establish a separate Scottish currency within the lifetime of the first, post-independence parliament. The pound sterling will remain in use until the currency transition.”

The CIC conference amendment would also scrap the six tests and remove a deficit reduction requirement it believes would result in public spending cuts.

The Herald on Sunday understands that at least six branches have submitted the amendment ahead of the conference.

One party insider said the currency issue is shaping up to be the SNP’s most substantive conference policy discussion since the debate on whether an independent Scotland should join NATO.

CIC chair George Kerevan said: “It’s clear there is a strong appetite amongst SNP members for a concrete plan for an independent currency without arbitrary caveats and stipulations and that would limit Scotland's ability to unchain itself from the chaos that is currently engulfing Westminster.

“The GC’s six tests could leave Scotland using the pound indefinitely, result in cuts to services and spending, and allow the City of London financial institutions to dictate an independent Scotland’s decisions. Sterlingisation and the six tests would effectively negate the very point of seeking independence for Scotland."

CIC Campaign Coordinator Rory Steel said:

“The level of support from SNP members and groups in such a short space of time demonstrates the growing opposition members have with the Growth Commission’s currency proposals.

“We’re looking forward to the discussion between members at party conference and we encourage branches to discuss our amendment in the meantime and offer their backing.”

Meanwhile, polling for Progress Scotland by Survation has found little support for an early replacement of the pound.

According to the organisation, more than 2,000 people took part in the poll, which was “particularly focussed on the views on people who are open-minded or undecided on Scottish independence”.

Asked about currency options in the event of independence, 47% expressed a preference for keeping the pound in the long term, while 23% backed a new currency in the longer term when economic tests have been met.

The polling found that 14% backed Scotland joining the Euro, while 6% supported switching to a Scottish currency in the short term.

SNP depute leader Keith Brown said: "The proposal I am putting to the SNP's spring conference would see an independent Scotland retain the pound until we can move safely and securely to establish a new currency, a decision that would be made in Scotland by a democratically elected Scottish Parliament.

"With independence, we can pursue a currency policy that's right for Scotland - maximising opportunities as a proud, successful European nation in a global economy."