White House Deputy Chief of Staff Kirstjen Nielsen will be nominated by President Trump to be the new Secretary of Homeland Security.
Trump's announcement could come as early as Wednesday, Politico reported, citing two administration officials and three outside advisers familiar with the matter.
Nielsen is an expert in homeland and national security policy and strategy, with a focus on critical infrastructure protection, according to her biography on GWU's Center for Cyber & Homeland Security.
News that she was viewed as one of Kelly's enforcers - someone who brought structure to the day-to-day operations at the White House, though some were frustrated by her direct style and role in limiting access to meetings and the Oval Office.
Mr. Kelly, who has relied on Ms. Nielsen's counsel and expertise since he was preparing for his January confirmation hearing to be Homeland Security secretary, had pushed hard for her selection.
Nielsen was retired Marine Corps General John Kelly's chief of staff when he was secretary of Homeland Security during the opening months of Trump's presidency.
Mr. Trump could announce his choice as soon as Wednesday, the people said, speaking on condition of anonymity because they were not authorized to make it public.
She is now the White House principal deputy chief of staff. The White House had no immediate comment. Increased border security and a possible overhaul of the immigration system remain top campaign promises Trump has yet to fulfill, including his trademark wall on the border with Mexico.
She's the first nominee to lead DHS to have previously worked there. She was responsible for carrying out some of Kelly's orders on who gets access to the president.