A “surge” in support for Scottish independence would force the UK government to back a new referendum, Nicola Sturgeon is to claim.
The Scottish first minister wants to hold a new vote on independence before the next Holyrood election in 2021.
The UK government has already ruled out granting consent during this period.
Ms Sturgeon will tell the SNP conference that a rise in support would show that nobody could “stand in the way” of another referendum.
She will be making her speech in Edinburgh the day after a majority of delegates went against her wishes and voted to change a new post-independence currency plan put forward by the party leadership.
The first minister told MSPs on Wednesday that she wanted to hold a second referendum on independence by 2021 if Scotland was taken out of the EU.
However she said she would want to get the agreement of the UK government beforehand, saying this would put the legal status of the vote “beyond doubt”.
The UK government has repeatedly said it would refuse any request for consent, with Cabinet Office minister David Lidington saying there was “no evidence that the appetite of the Scottish people to go through a referendum once again has surged up”.
Ms Sturgeon will tell her party’s members that “Scotland needs the choice of a better future – an independent future”.
She is to say that polls have shown increased support for independence, and that “our job now is to get it surging, and ensure that no Tory government can ever stand in the way of Scotland’s right to choose”.
She will add: “The UK government says it will block Scotland’s right to choose. A right to choose mandated in not just one but two Scottish elections. And endorsed by the Scottish parliament.
“The Tories say they and not the people of Scotland will decide. They say Westminster should have a veto.
“Their only friends in Parliament are the Democratic Unionist Party. Well, if they’re not careful, this generation of Tories will go down in history as the Undemocratic Unionist Party.”