• William Barr to replace outgoing Justice Department chief Jeff Sessions.

President Donald Trump told reporters on Friday that he'll nominate Heather Nauert, the State Department spokeswoman and one of the country's highest-ranking diplomats, to replace Nikki Haley as the US ambassador to the UN.

Trump also announced on Friday that he'll nominate

Haley abruptly resigned in October — a move she said she had discussed with Trump for months — and is set to leave by the end of the year.

Nauert, 48, has for months balanced two high-profile positions at the State Department after Trump picked her to be acting undersecretary for public affairs and public diplomacy. And while Nauert is generally well-liked by her colleagues, many say she lacks the necessary experience for her jobs and is overloaded with responsibility.

There has never before been a State Department spokesperson who has simultaneously served in that undersecretary role, a top-ranking post that directs strategic messaging, promotes cross-cultural exchanges, and oversees the Global Engagement Center, which fights foreign propaganda.

And unlike most of her predecessors in both roles, Nauert, a former Fox News host, arrived in Washington last year without experience in foreign policy, government or politics.

Reports had also surfaced in recent months that Nauert was high on the administration's list of potential replacements for the White House press secretary Sarah Huckabee Sanders, who is said to be considering leaving around the end of the year. Sanders has publicly denied reports that she plans to leave.