UPDATE 1-U.S. Homeland Security Secretary Nielsen expected to resign -report

U.S. Department of Homeland Security Secretary Kirstjen Nielsen is expected to submit her resignation to President Donald Trump, CBS News reported on Sunday, citing two unnamed officials.

CBS said it was unclear whether her departure would be voluntary. Nielsen, 46, has held the position since December 2017. She leads a sprawling department responsible for carrying out some of Trump's most contentious policies, such as his plan to build a wall on the border with Mexico and the separation of migrant children from their families.

The Department of Homeland Security did not immediately respond to a request for comment. It was not the first time that Nielsen's supposed departure has been reported. The Wall Street Journal reported in November that Trump had decided to replace Nielsen.

(Reporting by Diane Bartz and Patricia Zengerle; Editing by Peter Cooney and Sonya Hepinstall)