Outgoing Homeland Security Secretary Kirstjen Nielsen announced Tuesday evening that her acting deputy secretary was leaving her post “effective tomorrow.” In a tweet, Nielsen said Claire Grady offered President Trump her resignation. “For the last two years, Claire has served [the Department of Homeland Security with] excellence and distinction,” Nielsen wrote. “She has been an invaluable asset to DHS—a steady force and a knowledgeable voice.” The Wall Street Journal reported on Monday that the White House was pushing Grady to resign in order to ensure Trump’s preferred pick—Customs and Border Protection Commissioner Kevin McAleenan—would take Nielsen’s place once she officially steps down on Wednesday. According to the Journal, Grady expressed to associates that she did not want to leave her post, but an administration official told the newspaper Grady was not “qualified to be secretary” and McAleenan was “far better equipped” to oversee immigration matters.