STIRLING, Scotland (Reuters) - The Scottish National Party is to send out thousands of its faithful to measure the appetite for independence, leader Nicola Sturgeon announced on Friday, raising the political stakes further as Britain decides how it will leave the European Union.

Scotland's First Minister Nicola Sturgeon speaks at the launch of the Scottish National Party's (SNP) "biggest ever political listening exercise", in Stirling, Scotland, Britain September 2, 2016. REUTERS/Russell Cheyne

The first minister of the devolved Scottish government said Britain’s June vote to leave the EU, dragging Scotland with it, had shifted the debate dramatically just two years after Scots voted by 10 percentage points to reject independence.

“Do we control our own destiny as a country or will we always be at the mercy of decisions taken elsewhere?” Sturgeon asked her Scottish National Party (SNP) lawmakers in Stirling, the site of a historic Scots battle over the English in 1297.

The SNP, funding the entire project itself, aims to have at least two million nuanced responses from Scotland’s 5.3 million population by November 30, Scotland’s national day via a survey and doorstep interviews.

Armed with that information and a better idea of what Brexit means, it can better decide whether and how to call another referendum - raising the stakes further for British Prime Minister Theresa May as she grapples with the thorny EU exit.

Scotland voted 62 percent to 38 to remain in the EU in the June 23 Brexit referendum, putting it at odds with Britain as a whole which voted to leave. The SNP says EU membership was a key factor in Scottish voters’ decision in 2014 to remain part of Britain.

Business leaders, in a letter to The Scotsman newspaper, called on Sturgeon to “think again”, saying a new independence campaign would bring further uncertainty “to Scotland’s future at a time when small and large businesses are looking for stability from all layers of government”.

Scottish Conservative leader Ruth Davidson accused Sturgeon of using the EU referendum to create yet more division.

“Re-heating the referendum debate will only add a further cloud of uncertainty over Scotland’s future, just at the moment when we need a government dedicated to security and stability.”

But Sturgeon took the Conservatives to task for “accidentally” taking the country out of the EU, and said staying in the single market was a red line for Scotland.

“This summer we witnessed seismic changes which will have a deep impact on our ambition for this country,” Sturgeon said. “The UK that existed before June 23 has fundamentally changed,” she said.

She would negotiate “in good faith” with London to get the best deal for Scotland and secession had to be an option too, she said.

“While I take nothing for granted, I suspect support for independence will be even higher if it becomes clear that it is the best or only way to protect our interests,” she said.

Some doubt Scotland would now opt for independence given that it rachets up economic uncertainty during an already clouded outlook due to Brexit.

But in a nod to her critics, Sturgeon vowed not to skirt the difficult economic questions and said a specially commissioned SNP group would consider an independence policy program aimed at expanding the economy, cutting fiscal deficit and deciding a monetary strategy.

Scotland’s fiscal deficit hit 9.5 percent of GDP in the year to March, more than twice that of Britain as a whole, hindered by a low oil price. That makes balancing the books tough without unpopular austerity measures which the SNP opposes.

The offer to keep the pound at the 2014 referendum and a dependence on oil as an asset were widely seen as weak points in the independence argument last time.

The party will have a deep trove of information on which to base its next steps by the time the shape of the Brexit negotiations in London and Brussels become clearer.

A YouGov poll published a week after the Brexit vote however showed most Scots still wanted to remain a part of Britain, by 53 to 47 percent. A YouGov poll in the Times newspaper on Friday put support for remaining at 54 percent to 46 percent.