Why the Resignation of a Key Scottish Leader Is a Sign the U.K. Could Break Apart Over Brexit

The leader of the Conservative Party in Scotland has quit her post one day after Prime Minister Boris Johnson moved to suspend Parliament ahead of Brexit.

Ruth Davidson cited family reasons in her decision to leave the job, but her distaste for Johnson was no secret.

Her departure could throw the unity of the U.K. into doubt. In her role, she was the most influential voice for Scotland remaining a part of the U.K. at a time when support for Scottish independence has risen amid widespread opposition to Brexit.

Davidson, who appeared on the 2018 TIME 100, campaigned successfully to keep Scotland inside the United Kingdom during the Scottish independence referendum in 2014.

And in 2017, she successfully brought the Conservatives back from the political wilderness in Scotland––winning 13 parliamentary seats, up from just one in the previous election. The total was enough to keep former Prime Minister Theresa May in power, amid a disastrous showing elsewhere in the U.K.

But her position was made more difficult when Johnson became Prime Minister in July. Johnson is widely seen as toxic in Scotland: earlier in August, a poll showed support for Scottish independence surpassing 50% for the first time since 2017.

Davidson––along with a majority of Scots––voted to remain in the E.U. in the 2016 Brexit referendum. But Johnson campaigned to leave, and has increasingly advocated Britain leaving the E.U. without a deal––which Davidson has said would be damaging to Scotland.

Davidson’s resignation will not change the parliamentary arithmetic around Brexit––she is a member of the Scottish Parliament in Edinburgh, not the British Parliament in Westminster––but it is a blow for the moderate wing of the U.K.’s ruling Conservative Party, where was seen as a key figure and rising star.

Her name had even been raised among Conservatives as a potential future party leader. But Davidson said she had no plans to try for the role — last year, she became the first U.K. party leader to give birth to a child in the job. She was also the U.K.’s first openly gay leader of a major political party.

Even before May resigned, Davidson and her allies reportedly mounted a secretive attempt to prevent Johnson from winning the ensuing Conservative leadership election. Its codename, “Operation Arse,” made clear her feelings toward Johnson.

In the aftermath of the Brexit referendum, support for the Scottish National Party, which is currently in power in Scotland and advocates Scottish independence, rose. But Davidson campaigned firmly to resist calls for a second independence referendum. With her gone, the calls for Scotland to secede from the U.K. may increase.