Transportation Secretary Elaine Chao is resigning effective Monday, becoming the highest ranking member of President Donald Trump’s administration to resign in protest after the pro-Trump insurrection at Capitol.

In a statement Thursday, Chao, who is married to Senate GOP leader Mitch McConnell, said the violent attack on the Capitol “has deeply troubled me in a way that I simply cannot set aside.”

She said her department will continue to cooperate with President-elect Joe Biden’s designated nominee to head the department, former South Bend, Indiana, Mayor Pete Buttigieg.