US Transport Secretary Elaine Chao on Thursday said she would resign over the storming of the Capitol by Donald Trump’s supporters, the highest-level resignation yet as the president’s administration is rocked by the violence.

Chao, who is married to Senate Majority Leader Mitch McConnell, said it was “a traumatic and entirely avoidable event as supporters of the President stormed the Capitol building following a rally he addressed.”

“It has deeply troubled me in a way I simply cannot set aside,” she added.

Chao said her resignation would take effect on Monday, just nine days before Trump is set to leave office.

Chao, a former Labor secretary and deputy transportation secretary under prior Republican presidents, has led the department for four years and said “will help my announced successor Mayor Pete Buttigieg, with taking on the responsibility of running this wonderful department.”