Scottish lawmakers on Tuesday begin a two-day debate on First Minister Nicola Sturgeon's call for an independence referendum -- a major headache for Prime Minister Theresa May as she prepares to launch Brexit.
The Scottish parliament's vote on Wednesday is widely expected to endorse Sturgeon's campaign to get the British government to agree to a second vote after a 2014 one in which Scots voted to stay in Britain.
The semi-autonomous Scottish government wants to ask the people of Scotland to reconsider their vote against independence with a new referendum before Britain is expected to leave the EU in 2019.
Sturgeon, leader of the ruling Scottish National Party (SNP), intends to use the Edinburgh parliament's voice to assert Scotland's "sovereign right" to choose its own future.
She said her Brexit compromise for Scotland to be allowed to remain in the European single market even as the rest of Britain leaves had been met with "a brick wall of intransigence" in London.
The Scottish parliament cannot hold a legally-binding referendum without London's consent -- and Conservative Prime Minister Theresa May has insisted that "now is not the time" for a vote.
But Sturgeon has said it would be "democratically indefensible" to block a referendum, although she has signalled she is willing to negotiate on a date.
"This crucial decision over our future should not be made unilaterally by me, or by the Prime Minister,? she said.
"It should be made by the people of Scotland, and I call on parliament to give the people that choice."
The SNP does not have an outright majority in Edinburgh, but it has already secured the support of the Green party for another independence bid.
Patrick Harvie, leader of the Greens, said: "I think Theresa May will be taking a huge risk... if she refuses to acknowledge that we have a right in Scotland to have a say about our future."
- 'No public or political consent' -
Scotland voted against independence by 55 percent in 2014, but the campaign left the unionist camp politically divided while nationalists flocked to the SNP in their droves.
The SNP won all but three Scottish seats in the British parliament in 2015 and Sturgeon stood for re-election to the Edinburgh parliament in May 2016 on a pledge to hold another independence referendum if Scotland was "dragged out" of the EU against its will.
The SNP gained twice as many votes as the other parties, and Scotland was indeed outvoted by England and Wales in the Brexit referendum the following month, sparking a fresh constitutional crisis.
But Sturgeon has yet to convince a sceptical electorate, with a series of recent polls showing support for independence has barely moved since 2014 -- including a Panelbase poll concluded on Friday which found it stood at 44 percent.
"We believe a referendum cannot happen while the Brexit process is being played out," said Scottish Conservative leader Ruth Davidson -- May's most senior representative in Edinburgh.
"We believe a referendum should not happen when there is no public or political consent for it to happen."
John Curtice, professor of politics at the University of Strathclyde, suggested May's intransigence and the current lack of public support for another referendum may actually work in Sturgeon's favour.
"The 'Yes' side still has considerable ground to make. More time to argue her case might, in truth, be just what Nicola Sturgeon wants," he said.