Nicola Sturgeon will update MSPs on her plans for a second Scottish independence referendum at Holyrood on Wednesday.
Her address to the Scottish Parliament on Scotland's political future will also cover the fallout from the Brexit turmoil at Westminster following the extension agreed until the end of October.
The SNP leader has been pledging to make a statement on her plans for a second independence referendum for months, but insisted she needed more clarity on Brexit before she could set out her thinking.
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It comes just days before the SNP gathers in Edinburgh for the party's Spring conference where delegates will step up plans for a new referendum campaign by agreeing to a separate Scottish currency after independence.
A meeting of Holyrood's parliamentary bureau on Tuesday will consider the change to scheduled business tomorrow afternoon, but this is expected to be a formality.
Leading figures in the independence movement, such as Greens co-leader Patrick Harvie, have been stepping up the pressure on Ms Sturgeon to forge ahead on the referendum issue, but the First Minister has urged caution as polls show no movement towards Yes.
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The UK Government has authority over the constitution , including referendums on independence, and Prime Minister Theresa May has previously insisted that "now is not the time" for a fresh vote on independence. Foreign Secretary Jeremy Hunt said in March that the UK government would "of course" refuse to give its backing to a new vote via a "section 30 order", the transfer of powers to Holyrood which underpinned the 2014 referendum.
The Tories have pointed to the SNP’s Holyrood manifesto launch in April 2016 when Sturgeon said that she would not bring forward a referendum before a majority of Scots wanted it. Polls indicate there is still no majority support for a Yes vote.