Britain lurched closer to leaving the European Union (EU) on Monday when Parliament stopped resisting and gave Prime Minister Theresa May the power to file for divorce from the bloc.
But in a blow to May's government, the prospect of Scotland's exit from the United Kingdom suddenly appeared nearer, too. Scottish First Minister Nicola Sturgeon called for a referendum on independence within two years to stop Scotland being dragged out of the EU against its will.
In an announcement that took many London politicians by surprise, Sturgeon vowed that Scotland would not be "taken down a path that we do not want to go down without a choice."
Sturgeon spoke in Edinburgh hours before the European Union (Notification of Withdrawal) Bill passed its final hurdle in Parliament's upper chamber, the House of Lords.
The House of Commons approved the bill weeks ago, but the 800-strong Lords fought to amend it, inserting a promise that EU citizens living in the United Kingdom (UK) will be allowed to remain after Britain pulls out of the bloc.
They also added a demand that Parliament get a "meaningful" vote on the final deal between Britain and the remaining 27 EU nations.
Both amendments were rejected on Monday by the Commons, where May's Conservatives have a majority. A handful of pro-EU Conservatives expressed their unhappiness, then abstained from the vote.
The bill returned to the Lords, in a process known as parliamentary ping pong. Faced with the decision of the elected Commons, the Lords backed down and approved it without amendments.
Labour peer Dianne Hayter, who proposed the amendment on EU citizens, said the Lords had done their best, but "our view has been rejected in the elected House of Commons, and it is clear the government is not for turning."
Once the bill receives royal assent — a formality that should be accomplished within hours — May will be free to invoke Article 50 of the EU’s key treaty, triggering two years of exit negotiations, by her self-imposed deadline of 31 March.
May was forced to seek Parliament's approval for the move after a Supreme Court ruling in January torpedoed her attempt to start the process of leaving the bloc without a parliamentary vote.
The House of Commons and House of Lords battled over the bill's contents, with the status of EU nationals in Britain — and Britons in fellow EU member countries — drawing especially emotional debate.
Both British and EU officials have said such residents should be guaranteed the right to stay where they are, but the two sides have so far failed to provide a concrete guarantee, leaving millions of people in limbo.
The government’s satisfaction at victory in Parliament was tempered by the prospect of an independence vote that threatens the 300-year old political union between England and Scotland.
Sturgeon said she would seek to hold a referendum between the fall of 2018 and the spring of 2019 so Scottish voters could make an "informed choice" about their future.
(This article has been edited for length.)