Tens of thousands of SNP supporters are to fan out across the country knocking on doors to find out if there is support for a second independence referendum.

First Minister Nicola Sturgeon, who says she will only hold a second poll when she knows it has the backing of voters, will today sound the drumbeat towards another vote as she launches what is billed as the biggest listening exercise in Scotland’s history. 

The SNP leader will kick-start ithe new push by warning in a speech in Stirling that the UK has “fundamentally changed” in the wake of June’s Brexit vote.

Thousands took part in the last ‘national conversation’ on independence, between 2007 and 2009, when ministers invited questions from the public at town halls across Scotland.

READ MORE: Sturgeon accused of a sham as opposition parties say they will oppose another independence referendum

Many more made their views clear online and the exercise culminated in a public consultation on a draft Referendum Bill.

Today’s launch comes amid intense speculation that Ms Sturgeon will set out legislation for a second referendum next week.

Amid turmoil in the Labour party and the prospect of successive Conservative governments dominating Westminster, the First Minister will argue that the time is right for a new national conversation.

She will say: “The debate now is whether we should go forward, protecting our place as a European nation or go backwards, under a Tory government with very different priorities.

READ MORE: Sturgeon accused of a sham as opposition parties say they will oppose another independence referendum

She will reiterate her pledge to look at very available option to safeguard Scotland’s relationship with the EU but the debate “must include an examination of independence”.

Scottish Liberal Democrat leader, Willie Rennie, said the First Minister is "only pretending to listen".

"Nicola Sturgeon has already decided that independence is the answer to Brexit

"With the chaos of Brexit we do not need further chaos with the threat of independence."

The announcement comes as both the Liberal Democrats and Labour confirmed they will oppose proposals for another independence referendum, meaning the SNP leader will have to rely on support from Green MSPs to pass a Bill through Holyrood.

READ MORE: Sturgeon accused of a sham as opposition parties say they will oppose another independence referendum

At the start of the summer Ms Sturgeon had revealed that officials would begin work on proposals for another independence referendum, to be held if it proved the “best or only way to protect our place in Europe”.

Both Labour and the Lib Dems backed a Holyrood motion authorising ministers to examine how Scotland maintains its links with the EU.

At the time Ms Sturgeon assured MSPs it was “not a vote for a referendum on independence”.

Scottish Lib Dem leader Willie Rennie said Ms Sturgeon had “betrayed” her own pledge.

“From that moment on, she has talked about little else, betraying those words she uttered in Parliament and consigning the consensus to the dustbin,” he said.

Independence was the “only solution” she offered, while showing a “remarkable degree of enthusiasm” for Brexit, he said.

“I know her activists believe this is a golden opportunity to win independence but she has a responsibility to lead the country, not just her party,” he added.

Scottish Labour leader Kezia Dugdale also made clear her opposition to another vote.

She said that her party’s manifesto was “very clear, we’re opposed to a second referendum in the lifetime of this parliament”.

Her comments also appeared to slap down Owen Smith, the Labour leadership candidate who said earlier this week that he would not oppose a second referendum.

A spokesman for the First Minister said: “Willie Rennie is profoundly mistaken... the position the First Minister laid out on June 24, and which Mr Rennie backed in a parliamentary vote, is unchanged.

“The First Minister is clear that protecting Scotland’s interests and our place in Europe is her starting point.

“As recently as last week, she made clear that the Scottish Government will use whatever influence it has to shape the best outcome for the whole UK...however, she has also been clear that the option of independence should be on the table if it becomes clear that it is the best or only way of safeguarding our interests.”

He also accused Mr Rennie of seeking attention for his “increasingly irrelevant party”.

Ross Greer, the Scottish Greens external affairs spokesman, accused Mr Rennie of flouncing off “in a huff” .

But he added that “all avenues” available to maintain on Scotland’s links with the EU must be exhausted.

The Scottish Conservative leader Ruth Davidson has called on the SNP to give up plans for a second independence vote.

She said that figures published earlier this month showing Scotland had a £14.8bn deficit last year showed “the cost of independence”.

Earlier this month Ms Sturgeon said that the “argument that the UK is somehow a safe harbour for Scotland is no longer true”.