Holyrood is expected to back First Minister Nicola Sturgeon’s call for a second independence referendum.
MSPs will vote at 17:30 on the motion allowing the Scottish government to open negotiations with Westminster on the timing of a fresh poll.
Ms Sturgeon wants the referendum held between autumn 2018 and spring 2019.
Prime Minister Theresa May said last week that now was not the time to hold a second referendum on Scottish independence.
She argued the focus should be on getting the best Brexit deal for the whole of the UK.
- Follow live coverage of the debate and vote
- Keep across @BBCPhilipSim’s tweets on the debate
- The BBC’s Sarah Smith on who speaks for the Scottish people
However, Ms Sturgeon said it was right to hold a vote within her timescale in order for the people of Scotland to be offered a choice between a “hard Brexit” and becoming an independent country.
On Tuesday members of the Scottish Parliament began a two-day debate calling for a Section 30 order from Westminster.
The order would be needed to allow a fresh legally-binding referendum on independence to be held.
The government is expected to win the vote with the support of the pro-independence supporting Scottish Greens – despite opposition from the Conservatives, Labour and Liberal Democrats.
On the first day of the debate Ms Sturgeon insisted that Scotland’s future should be decided by the people who live there rather than being “imposed upon us”.
Scottish Conservative leader Ruth Davidson claimed voters were “sick to death of the SNP’s games” over independence as the pro-UK opposition parties argued that there was no appetite for another referendum just two and a half years after the first one.
In September 2014, voters in Scotland backed staying a part of the UK by 55% to 45%.
What does the parliamentary motion say?
“That the parliament acknowledges the sovereign right of the Scottish people to determine the form of government best suited to their needs and therefore mandates the Scottish government to take forward discussions with the UK government on the details of an order under section 30 of the Scotland Act 1998 to ensure that the Scottish Parliament can legislate for a referendum to be held that will give the people of Scotland a choice over the future direction and governance of their country at a time – and with a question and franchise – determined by the Scottish Parliament, which would most appropriately be between the autumn of 2018, when there is clarity over the outcome of the Brexit negotiations, and around the point at which the UK leaves the EU in spring 2019.”
MSPs expected to back call for second Scottish independence vote}