MSPs are expected to back Nicola Sturgeon's call for a second independence referendum in a vote at Holyrood today.
A two-day debate over whether the First Minister should seek permission to hold another ballot between autumn next year and spring 2019 started in the Scottish Parliament last week but was halted as news of the terror attack at Westminster emerged.
The vote was delayed but will be held on Tuesday, with the Scottish Greens expected to help the minority Scottish Government pass its motion asking for a mandate to take forward discussions with the UK Government on the details of a section 30 order, the mechanism to transfer the legal powers for a vote.
Ms Sturgeon met Theresa May in Glasgow on Monday and the Prime Minister has said ''now is not the time'' for another vote, indicating she will reject the SNP's preferred timetable.
Following their discussions, the First Minister insisted the Prime Minister had been clear the terms of the UK's divorce from the EU and the details of a new free trade deal would be known within two years.
''I think it makes it very difficult for the Prime Minister to maintain a rational opposition to a referendum in the timescale I have set out,'' Ms Sturgeon said.
Opening the referendum debate last Tuesday, the First Minister told the Scottish Parliament it would be ''wrong, unfair and utterly unsustainable'' for the UK Government to block her request.
About 62% of Scottish voters backed the UK remaining part of the EU in June 2016 and the SNP manifesto for last year's Holyrood elections made clear another ballot on independence should take place if there were a ''material change in circumstances'' from the previous ballot in 2014.
The example cited was for Scotland to be removed from the EU against its wishes.
Scottish Conservative, Labour and Liberal Democrat politicians have made clear they will vote against another referendum.
On the first day of the debate, Ms Sturgeon said: ''In the circumstances we now face, for the UK Government to stand in the way of Scotland even having a choice would be, in my view, wrong, unfair and utterly unsustainable.''
Scottish Conservative leader Ruth Davidson insisted the majority of Scots did not want another referendum now.
''This referendum may be the First Minister's priority. It is not mine. Nor that of my party,'' she said.
Scottish Labour leader Kezia Dugdale also opposed a second vote: ''Brexit isn't the motivation for another referendum, it's just the latest excuse."