FILE PHOTO - U.S. Homeland Security official Claire Grady attends a news conference during a meeting of the Interior ministers of G7 nations in Paris, France, April 5, 2019. REUTERS/Charles Platiau

WASHINGTON (Reuters) - U.S. Homeland Security Secretary Kirstjen Nielsen said on Tuesday that Claire Grady, the acting deputy secretary of the department, had offered her resignation to President Donald Trump, potentially further destabilizing the agency tasked with managing immigration and the country’s borders.

The departure of Grady, who was legally supposed to take over from Nielsen after Nielsen’s own ouster earlier this week, was expected after Trump picked U.S. Customs and Border Protection Commissioner Kevin McAleenan to become the acting head of the Homeland Security Department.

Nielsen’s resignation at the department is effective on Wednesday.