Amber Rudd quit as U.K. Home Secretary after an immigration scandal, stripping Prime Minister Theresa May of a pro-European ally and destabilizing her government just as internal battles over Brexit come to a head, Bloomberg reports.

Rudd, 54, was due to address lawmakers in the House of Commons on Monday to defend herself against allegations that she misled Parliament over targets for deporting illegal immigrants. May’s office confirmed she had resigned late on Sunday. No successor has been named yet.

Rudd’s departure comes at a critical time for May’s government. Rudd was due to be attending a key meeting of the Brexit “war cabinet” on Wednesday to weigh the options for the U.K.’s future trading relationship with the European Union. Her resignation will change the dynamic in that meeting — and, depending on who replaces her, could shift the Cabinet balance in favor of a harder Brexit.

Rudd was a key pro-EU voice who provided a counterpoint to pro-Brexit heavyweights, including Foreign Secretary Boris Johnson and Environment Secretary Michael Gove.

©2018 Bloomberg L.P.