by ALI VITALI and KRISTEN WELKER

WASHINGTON — Omarosa Manigault Newman, a White House aide and former "Apprentice" contestant, resigned Tuesday evening, Press Secretary Sarah Huckabee Sanders told NBC News, "to pursue other opportunities."

Her departure will not be effective until Jan. 20, the White House said, exactly a year from the day President Donald Trump was sworn in.

A White House official told NBC News that the president spoke with Newman by phone Wednesday and the two had a "nice" conversation that the official described as "very cordial."

The timing of her departure was unexpected, the official said, but noted that the president is more fond of her than people might realize.

That's likely due to their long history together. Trump later Wednesday tweeted, "Thank you Omarosa for your service! I wish you continued success."

Newman came to know Trump during her time as a controversial contestant on several seasons of his reality TV show, "The Apprentice." Her brash and manipulative persona on the show both endeared her to Trump and made her a must-watch character.

During the 2016 presidential campaign, Newman rallied crowds ahead of the then-candidate, traveling the country with an informal group of other "women for Trump" to make the case for the candidate. (Trump's daughter-in-law, Lara Trump; pro-Trump surrogate Katrina Pierson; and YouTube stars Diamond & Silk were also part of the group, who sometimes sported matching pink jackets.)

Newman was one of Trump's highest-profile African-American female supporters and one of the few black women in Trump's West Wing. Her title was assistant to the president and communications director for the Office of Public Liaison.

News of her departure comes less than a week after another high profile woman in the administration, Deputy National Security Advisor Dina Powell, announced she would leave at year's end.

Speculation has abounded in recent weeks about what other principle members of the administration are seeking an exit ramp, with Secretary of State Rex Tillerson — who, as NBC News and others have reported, has clashed with Trump — coming under close scrutiny.

Earlier this month, a White House source confirmed to NBC News that there was a plan being discussed to replace Tillerson with CIA Director Mike Pompeo, who has grown close to the president over the months.

At the time of the reports, State Department spokeswoman Heather Nauert told reporters that Tillerson "enjoys this job" and continues to do his work, adding that the secretary "serves at the pleasure of the president, as we all do."

A White House official, who spoke on condition of anonymity with NBC News, said that Tillerson's allies in the administration were scarce after months of clashing with the president. "He's burned all his bridges," the source said.