The party’s depute leader Keith Brown said MPs, MSPs and activists would be given a target of speaking to 50,000 people across the country on 29 September.

Revealing the plans in an interview with The Scotsman’s sister title inews.co.uk, he said the party would be “making the case for an independent Scotland” on the doorsteps by mobilising its sizeable membership.

Earlier this month it was confirmed that the SNP had become the UK’s second largest political party, with 125,000 members to the Conservatives’ 124,000.

The partys depute leader Keith Brown said MPs, MSPs and activists would be given a target of speaking to 50,000 people across the country on 29 September. Picture: John Devlin/TSPL

Mr Brown said the day of action would allow the SNP to take a “huge sample of public opinion”, arguing that the time was right to make the case for independence given the “chaos of Brexit”.

Citing a recent poll which found that Brexit could sway support in favour of Scottish independence, Mr Brown said he wanted activists to “mine that seam” by talking to voters.

“What’s really important now is taking that message out, right in the teeth of the chaos of Brexit, to put forward our proposition of why we believe Scotland should be independent,” he said.

While the party has been running street stalls to attract the attention of voters, taking its message onto the doorsteps marks a step up in its preparations for another referendum on independence.

However, Mr Brown also suggested that plans for a re-run of 2014’s vote may have to be pushed back if the timetable for the Brexit negotiations slips.

“It’s not fair to confront people with another constitutional question when the constitutional question of Brexit is as yet unresolved,” he said.

SNP activists will be instructed to seek voters’ views on the Growth Commission report, which attempted to reboot the economic case for independence, as well as other issues.

“People just now are seeing things like their mortgages going up because interest rates are going up, the cost of food is going up, they’re hearing stories about potential food shortages, about huge queues at the borders, they’re seeing the Tory party tearing themselves apart,” Mr Brown added.

“These things do tend to change the political environment: the perceived competence or otherwise of a government and the extent to which it’s seen to be in control of events is a big factor for people. We want to find out how people are feeling about that.”

The day of action is also part of the SNP’s preparations for a possible snap general election, with Mr Brown revealing that the vetting process for new candidates is already well under way.

“This is putting people on the streets, which is really important. With 50-odd Tory MPs talking about taking out the Prime Minister and installing another leader, and the manoeuvres that Boris [Johnson] is on, it seemed a sensible idea.”

Scottish Conservative chief whip Maurice Golden said the day of action would merely remind Scots that the SNP “continues to obsess over one thing” at the expense of the nation.

SNP activists to hold '˜day of action' on independence referendum