Omarosa was only African-American earning the top White House salary

Omarosa Manigault Newman, a senior staffer who recently departed the White House and the only African-American drawing a top salary, said Thursday the "lack of diversity" was a challenge she grappled with.

"It has been very, very challenging being the only African-American woman in the senior staff," Manigault Newman told ABC News' "Nightline" on Thursday.As top communications official at the White House Office of Public Liaison, Manigault Newman was charged with African-American outreach and said she regrets that the administration hasn't reached the level of diversity she "strove to see."White House press secretary Sarah Sanders on Thursday maintained that despite Manigault Newman's departure...