Nicola Sturgeon has insisted she would have no right to rule out holding a second independence referendum if polls produce "strong and consistent" evidence that the majority of Scots want to leave the UK.
The Scottish First Minister said she respected the result of last year's ballot, which saw voters reject independence by 55% to 45%.
She warned David Cameron that cuts from Westminster, together with the planned renewal of the Trident nuclear deterrent and other factors, could see support for independence rise.
Two polls since last September's referendum have suggested a majority of Scots want to exit the Union.
With support for the SNP continuing to grow, there has been constant speculation about when a new vote on the issue could take place.
Ms Sturgeon said: "To propose another referendum in the next parliament without strong evidence that a significant number of those who voted No have changed their minds would be wrong and we won't do it.
"It would not be respecting the decision that people made."
But the SNP leader added: "Over the next few years, as the Tories impose even deeper cuts, press ahead with Trident renewal and fail to honour in full the vow of more powers for our Parliament, I think support for independence will continue to rise.
"So let me also be clear about this. If there is strong and consistent evidence that people have changed their minds and that independence has become the choice of a clear majority in this country, then we have no right to rule out a referendum and we won't do that either.
"No one has the right to stand in the way of democracy."
She spoke out as she addressed the SNP conference in Aberdeen – the largest gathering the party has ever staged.
With the Conservative government planning to stage a referendum on the UK's membership of the European Union, the First Minister warned that if Scotland was removed from the EU "against our democratic wishes" on the basis of votes in England, that demand for another ballot on independence could be "unstoppable".
She sent a direct message to the Prime Minister, saying: "Let me say this to David Cameron. Last year, you told the Scottish people that the only way to protect our EU membership was to vote No. It was one of the central issues of your campaign.
"If you try to take Scotland out of the EU against our democratic wishes, you will be breaching the terms of last year's vote.
"And, in those circumstances, you may well find that the demand for a second independence referendum is unstoppable."
But with the SNP aiming to win an historic third term in office at Holyrood in less than seven months time, much of Ms Sturgeon's speech was focused on the upcoming Scottish elections.
She pledged the SNP would "set out radical, ambitious and progressive policies to make this country even stronger".
As part of that she promised that an SNP government would build at least 50,000 affordable new homes over the next parliamentary term if it wins in May - of which approximately 35,000 would be new council or housing association properties.
No party has ever won a third term in office in the devolved Scottish Parliament, but Ms Sturgeon told SNP delegates: "If we are re-elected next May, our target in the next parliament will be to build at least 50,000 new affordable homes.
"That commitment - worth more than £3 billion - is a mark of the ambition we have for this country.
"Ambition for Scotland and for everyone who lives here will be the hallmark of our campaign for re-election."
While the SNP has "record approval ratings in the polls" in Scotland, Ms Sturgeon insisted her party would "campaign harder than we have ever done to win".
Next year's Scottish Parliament elections will be Ms Sturgeon's first as party leader and First Minister.
She told the conference: "Next May, I will ask the people of Scotland, for the first time, to elect me as First Minister. And we, together, will seek what no party in the devolution era has yet achieved – a third term in office."
She added: "We must convince the people of this country that I will be the best First Minister, that we are the best team, and that we have the best policies and the best vision to lead Scotland confidently into the next decade."
The SNP leader said she wanted those who had rejected independence last year to back her party for a third term in government.
"I don't want to just win the votes of independence supporters," Ms Sturgeon stated.
"I want to inspire people who voted No to vote SNP too. I want them to vote SNP because we are the best party, with the best ideas and the best people to lead Scotland forward."
In the general election this year, the SNP swept the board in Scotland, winning all but three of the 59 seats that were up for grabs.
Ms Sturgeon said the SNP in Westminster are "the only party with the unity and the conviction to stand strong against austerity".
After 21 Labour MPs rebelled against new leader Jeremy Corbyn last night and voted for the Conservative Charter of Budget Responsibility, its "divisions were laid bare".
Ms Sturgeon said: "There is much that I hoped the SNP and Jeremy Corbyn could work together on. But over these last few weeks, it has become glaringly obvious that he is unable to unite his party on any of the big issues of our day.
"When he says he opposes Trident, he is attacked, not just by the Tories, but by his own shadow cabinet."
In contrast she said the SNP "stands against Trident today, tomorrow, always".
The First Minister continued: "Whether on the economy, or Trident, or even the question of whether UK forces should take part in air strikes on Syria, Labour is a party divided and in disarray.
"In fact, the only thing clear about Labour, and it becomes clearer by the day, is this - Labour is unreliable, unelectable and unable to stand up to the Tories."
Ms Sturgeon went on: "As Labour becomes ever more divided, the Tories, under the cloak of centrist rhetoric, threaten to even more deeply divide our society.
"Tax credit cuts for the lowest paid, repeal of the human rights act, attacks on trade union freedoms and disgracefully divisive language on immigration. This is not a Tory government moving to the centre, this is a Tory government trying to shift the centre ground of British politics sharply to the right."
She added that the SNP could "counter this shift" by opposing the Conservatives at Westminster and by governing at Holyrood "showing there is a better way, directly benefiting people in Scotland and providing a beacon of hope to people across the UK".
