Scotland's First Minister Nicola Sturgeon is to demand that Scotland be allowed to hold a second referendum on independence.
Ms Sturgeon will tell the Scottish National Party conference in Edinburgh that a recent poll shows support for independence has risen.
On Thursday, Prime Minister Theresa May's effective deputy David Lidington said he saw no evidence from Scottish people for changing the decision they took in 2014.
But after polling by YouGov showed support for Scotland leaving the UK had gone from 45% last summer to 49%, Ms Sturgeon will tell the SNP conference that the Tories are already being proved wrong.
The First Minister will address party activists just days after telling MSPs there should be a second independence referendum before the next Holyrood election in May 2021 - suggesting later that such a ballot could take place even if Brexit does not go ahead.
"It is time - time for Scotland to become independent," the SNP leader will say in her keynote speech.
"The last three years have shown, beyond any doubt, that for Scotland the Westminster system is broken.
"Scotland needs the choice of a better future. Scotland needs an independent future."
And while she will say the "UK government says it will block Scotland's right to choose", she will insist there is a mandate for a referendum from "not just one but two Scottish elections" which has also been endorsed by the Scottish Parliament.
Hitting out at Conservatives on the issue, she will say that while "their only friends in Parliament are the Democratic Unionist Party", Mrs May and her party could "go down in history as the Undemocratic Unionist Party".
The SNP leader will tell the conference: "On Thursday, they tried to justify their position by saying there was no upsurge in support for independence.
"Two days later the latest opinion poll was already proving them wrong.
"It shows support for independence already up. So 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."
