LONDON (AP) — Scottish First Minister Nicola Sturgeon is set to deliver a statement Tuesday setting out how she believes a new referendum on Scottish independence could be held.

Scottish voters rejected independence in a 2014 referendum, with 55% of voters saying they wanted to remain part of the United Kingdom.

But Sturgeon, who leads the Scottish National Party and the devolved government in Scotland, has said it's time to revisit the matter because of changes brought about by Brexit. She wants a new vote on independence before the end of 2023.

That would need a green light from the U.K.-wide government of Prime Minister Boris Johnson, who opposes a new referendum and has said the issue was settled in the 2014 vote.

Sturgeon maintains that her party's success in local elections last year gives her a mandate for a fresh referendum. While the Scottish National Party did not win overall control in the Scottish Parliament, the election of a record number of Scottish Green lawmakers means there is a majority for a new independence vote.

“Westminster rule over Scotland cannot be based on anything other than a consented, voluntary partnership," Sturgeon said ahead of delivering a speech to Scottish Parliament.

“It is time to give people the democratic choice they have voted for, and then with independence to build a more prosperous, fairer country in a true partnership of equals between Scotland and our friends in the rest of the U.K.," she added.

Opposition parties have criticized Sturgeon for her “obsession” with holding a new independence vote and say she should instead be focused on more practical matters such as tackling the soaring cost of living.

Like Wales and Northern Ireland, Scotland has its own parliament and devolved government and makes its own policies on public health, education and other matters. But the U.K.-wide government in London controls matters such as defense and fiscal policy.