Kelly has said at least twice that he and the president "have an incredibly candid and strong relationship". Practically since inauguration various factions have been vying for political supremacy in the West Wing.
US First Lady Melania Trump has publicly pushed for the dismissal of deputy national security advisor Mira Ricardel - a rare criticism of a senior administration official by the president's wife.
Mr Trump is said to be resigned to the departure of Mr Kelly, 68, the retired Marine Corps general who has served as his highest-ranking White House aide since July previous year after...
A DHS official who spoke on the condition of anonymity told the Post that Trump needs to nominate a replacement who has "executive-branch experience" to help the department run more smoothly. Curbing immigration is Trump's signature issue - and one he returns to as a way to rally his most loyal supporters. Kelly has been protective of Nielsen, who he has worked with for many years.
Nielsen has reportedly been disgruntled with her job, as Trump has berated her during Cabinet meetings and branded her a "Bushie" months ago, as she used to serve under President George W. Bush. Some of the sources allegedly close to the president told ABC that picking Ayers instead of Kelly was a "done deal", yet others were less certain.
Even one NSC official who said they liked Ricardel said she "liked to pick fights with a lot of different folks" and suspected her latest feud with the first lady's office was "the last straw".
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Questions about Nielsen's job security are not new.
Ricardel has been key to Bolton's efforts to restructure the National Security Council and to help Bolton secure his place as an influential adviser to the President on all foreign policy matters.
Nielsen has led the sprawling post-9/11 federal agency since December.
A spokesman for the Department of Homeland Security declined to comment on Nielsen's potential departure. She was tasked with helping states secure elections following interference by Russians during the 2016 election. "Could it be that it's not completely verified and true?" she said. But she was also instrumental in stopping the separations. The decision would affect about 70,000 people annually and was immediately challenged by the American Civil Liberties Union.
Nielsen has taken the blame within the administration for an uptick in migration across the southern USA border.
At the peak of controversy over the Trump administration's "zero tolerance" family-separation initiative, Nielsen nonetheless stood at the White House lectern and delivered a vigorous defense of the measures. It was not immediately clear when she would officially make her exit.