Nicola Sturgeon will today publish the second in a series of papers aimed at convincing Scots of the benefits of independence.
The First Minister will hold a press conference at Bute House in Edinburgh where she will answer questions on her government's push to hold a second referendum.
The SNP leader last month told MSPs her intention was to hold an IndyRef2 on October 19 next year - but only if Supreme Court judges declared such a plan was legal.
The UK Government has so far refused to grant a Section 30 order which would temporarily loan Holyrood the legal powers required to stage a referendum.
Sturgeon is set to blast Westminster's position and claim Scotland faces a "democratic deficit" as a result.
The First Minister is expected to say: "This discussion could not be more timely or urgent - the democratic deficit Scotland faces is not a recent phenomenon, but the evidence of it now is starker than ever.
"A Prime Minister with no democratic endorsement from Scotland is about to be replaced by yet another Prime Minister that Scotland hasn’t voted for - and wouldn’t vote for even if we were given the chance.
"All Scotland ever hears from UK politicians these days is democracy denial. They trade opinions on how many years it should be before Westminster might ‘allow’ us to make a democratic choice about our own future.
"The fact that the Scottish people have repeatedly elected a majority in the Scottish Parliament committed to an independence referendum is treated as immaterial. You don’t have to be a supporter of independence to know that’s not democracy.
"That attitude is not surprising from Tories - but these days, where the Tories go, Labour seem obliged to follow. Just as in 2014, they are teaming up with the Tories to frustrate the will of the Scottish people."
She will add: "What Scotland is hearing and seeing, on a daily basis, from Westminster parties encapsulates the democratic deficit that we face as part of the UK.
"Parties and policies that we reject are to be forced upon us - but the democratic right to choose an alternative is to be denied to us."
In one of his final acts before announcing his intention to resign as Prime Minister, Boris Johnson wrote to Sturgeon last week to dismiss her call for an IndyRef2.
Johnson wrote: "I have carefully considered the arguments you set out for a transfer of power from the UK Parliament to the Scottish Parliament to hold another independence referendum.
"As our country faces unprecedented challenges at home and abroad, I cannot agree that now is the time to return to a question, which was clearly answered by the people of Scotland in 2014."
