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PA via AP, Andrew Milligan
Scottish Independence supporters hold flags and banners outside the Scottish Parliament in Edinburgh ahead of the vote by Members of the Scottish Parliament to hold a second Scottish independence referendum Tuesday March 28, 2017. On Monday British Prime Minister Theresa May has met Scotland's leader Nicola Sturgeon for the first time since they faced off in a struggle over a new push for Scottish independence as the U.K. leaves the European Union. 

EDINBURGH, Scotland — Scotland's parliament is set to vote Tuesday on a call by First Minister Nicola Sturgeon for a referendum on Scottish independence within two years.

Sturgeon says Scots must be given the chance to vote on their future before Britain leaves the European Union. British Prime Minister Theresa May plans to launch the U.K's two-year process to exit the EU on Wednesday by triggering Article 50 of the bloc's key treaty.

"Scotland's future should be in Scotland's hands," Sturgeon told lawmakers in the Edinburgh-based parliament.

Scottish voters rejected independence in a 2014 referendum that Sturgeon's Scottish National Party called a once-in-a-generation vote. But Sturgeon says Brexit has changed the situation dramatically.

She says there should be a new vote on independence between fall 2018 and spring 2019, when details of Britain's divorce terms with the bloc are clear.

Sturgeon said that whatever the final terms, Brexit would mean "significant and profound" change for Scotland.

"That change should not be imposed upon us," she said. "We should have the right to decide the nature of that change."

May, whose government must approve the referendum for it to be legally binding, says the time is not right. She says all parts of the U.K. — England, Scotland, Wales and Northern Ireland — must pull together to get the best-possible deal with the EU.

Scottish Conservative leader Ruth Davidson agreed, saying Tuesday that Scots do not want "the division and rancor of another referendum campaign."

The Scottish parliament had been due to vote on Sturgeon's referendum demand last week, but the session was adjourned after Wednesday's terrorist attack in London.

The measure is likely to be approved Tuesday, with backing from the governing Scottish nationalists and the Greens.

But it's unclear what could break the stalemate between Edinburgh and London.

Sturgeon told Scottish lawmakers she would seek to negotiate with the British government, "in good faith and with a willingness to compromise."

Should that fail, she promised to inform the parliament of next steps after its Easter break next month.

Lawless reported from London.