"I have confidence that Kevin will do a great job!"
Nielsen was a close ally and confidante of Kelly, who left the administration at the end of 2018, marking a dramatic shift in the power dynamics of the West Wing, and there was continuing tension between Trump and Kelly over how the president treated her.
Nielsen was scheduled to meet with the president at 5 p.m.in the White House residence about border security, but sources told ABC News that the meeting turned into a discussion about Nielsen's future. Nielsen was unaware what was happening until after the nomination had been pulled, a person familiar with the news said.
Though Trump aides were eyeing a staff shake-up at Homeland Security and had already withdrawn the nomination for another key immigration post, the development Sunday was unexpected.
Arrests all along the southern border have skyrocketed in recent months.
The role didn't gain her popularity, but it helped her gain enough of Trump's trust to elevate her to the Cabinet post.
She didn't then, and went on to become one of the public faces of a controversial policy that separated undocumented children from their parents. Nielsen was seen as Kelly's protegee.
Mr Trump had threatened to fire Ms Nielsen and she has previously considered resigning, but officials at the time recognised there were no obvious successors in place. Nielsen, who served in President George W. Bush's administration, never overcame internal skepticism about her allegiance to Trump.