Department of Homeland Security Secretary Kirstjen Nielsen is expected to offer her resignation at a meeting at the White House on Sunday, U.S. officials familiar with the matter say. Nielsen was set to meet with President Trump at 5 p.m., the officials said.
Nielsen's expected departure is a part of a massive DHS overhaul engineered and directed by top Trump adviser Stephen Miller, according to a senior U.S. official. It's unclear whether Nielsen is deciding to resign voluntarily, or whether she has been pressured to resign. Nielsen has served as DHS secretary since December 2017, and questions about how much longer she might last have swirled for months, as the president continues to articulate his frustrations about illegal immigration.

Nielsen's anticipated exit also comes after Mr. Trump announced that he wants to go in a "tougher" direction for Immigration and Customs Enforcement director, after previously announcing Ron Vitiello would head ICE.
An official tells CBS News that Customs and Border Protection Commissioner Kevin McAleenan is under consideration to serve as the acting DHS secretary if Nielsen's resignation becomes official, but it is unlikely he would be nominated as Nielsen's permanent replacement.
In recent days, Mr. Trump has threatened to shut down the U.S.-Mexico border or slap tariffs on cars made in Mexico coming into the U.S., if Mexico and Congress don't fix the situation at the border.
This is a developing story and will be updated.