If she gets the job, Nauert would take the post with less clout than Haley, a former SC governor who announced in October that she would step down at the end of this year.
A White House insider told him: "With all the stink attached to the State Department, she's one person who all the Trump people know is a Trump person".
With no policymaking or negotiating experience, and after 20 months as a spokeswoman for the state department, Nauert will take her seat on the security council alongside counterparts with decades of experience.
Nauret now faces Senate approval and will need to tackle questions on her lack of experience in the field.
Aaron David Miller of the Wilson Center says Nauert has a different profile from past US ambassadors to the United Nations.
While Nauert struggled during the tenure of former Secretary of State Rex Tillerson - so ostracized from his inner circle that she considered quitting - she could now bring to the United Nations close ties to the White House and a good working relationship with Secretary of State Mike Pompeo.
Nauert is said to be close to both those in the White House and Secretary of State Mike Pompeo, and she has traveled extensively with the secretary, including to North Korea. I think about sleeping in. I do.
She has also worked as a general assignment reporter for ABC News. She is a quick study. "But, I think it [the USA ambassador job] is not going to be what it was under Nikki Haley, which was a serious competitor under a vacuum at the NSC [National Security Council] and at the State Department under [former Secretary of State Rex] Tillerson".
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"She's clearly not qualified for this job, but these days it seems that the most important qualification is that you show up on Donald Trump's TV screen", Democratic Senator Chris Murphy said on CNN.
Previously, she was a Fox News presenter and correspondent.
US State Department spokesperson Heather Nauert arrives for the release of the 2017 Annual Report on International Religious Freedom on May 29, 2018, in the Press Briefing Room at the US Department of State in Washington, DC.
UN Secretary-General Antonio Guterres "very much looks forward to working with Ms Nauert when she assumes her post and continuing the very productive and strong working relationship he enjoyed with Ambassador Haley", UN spokesman Stephane Dujarric told reporters.
Here are the top facts that could provide an exhaustive look at the U.S. president's pick for the top United Nations role, largely seen as a stepping stone to assuming more senior roles in government.
"With Pompeo more firmly in control and Bolton focused on his anti-multilateral agenda, there's a sense the U.S. ambassador will have less clout", Gowan said.
Haley herself arrived at the United Nations with little foreign policy experience beyond promoting worldwide investments in SC.
Unlike Haley, however, Nauert is not expected to have cabinet status, keeping power over foreign policy firmly with Pompeo and especially John Bolton, the hawkish White House national security advisor. "Ambassador Haley was a far more high-level figure, particularly early in the administration".