Mrs. Trump's office said Tuesday that Ms. Ricardel, deputy to National Security Adviser John R. Bolton, "no longer deserves the honor of serving in this White House".
But Nielsen remained in her job on Wednesday, two days after the Washington Post first reported that Trump planned to remove her, and she travelled to the border with Defense Secretary James Mattis to review the work of U.S. soldiers Trump deployed before the midterm elections last week.
A White House official was blunter, describing the California native as ideologically driven and "obstinate".
In locking horns with the First Lady, she seems to have come off second best to the person the president trusts the most - his wife. He thought it "made him look like a bossed-around husband", Jake Tapper reported. She also believed that Ricardel spread rumours about her.
White House Press Secretary Sarah Sanders announced in an end-of-day statement that Ricardel 'will continue to support the President as she departs the White House to transition to a new role within the Administration'.
However, Sanders would not say which position she will be moving into. Aides had said Ricardel had pushed for a seat to be reserved on the first lady's plane for a National Security Council representative to brief her during the trip.More news: David Pearson, NASCAR legend, passes away
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But Mr Bolton rebuffed the first lady and protected his deputy, prompting the first lady's spokeswoman, Stephanie Grisham, to issue an extraordinary statement to reporters effectively calling for Ms Ricardel to be fired.
Another source said that Mrs Trump felt that Ms Ricardel tried to short-change the first lady in terms of USA government resources allocated to support her Africa tour.
The Wall Street Journal reported Tuesday that Ricardel had gotten into a fight with the first lady's staff over resources needed for Melania's Africa trip last month.
Trump again called the investigation "highly conflicted".
She went on to hold positions in three Republican administrations, working in the departments of State, Defense and Commerce, as well as acting as an aide to then Republican Senate leader Bob Dole.
"I am deeply grateful for all Mira has done on behalf of the NSC, her deep knowledge of the national security issues we confront daily, and her unwavering commitment to the President", Bolton told staff.