WASHINGTON — President Trump plans to nominate Heather Nauert, the chief State Department spokeswoman, to become his next ambassador to the United Nations as he moves to reshape his team for the final two years of his term, two people familiar with the choice said on Thursday.

Ms. Nauert, a former Fox News anchor who has served as the public face of the State Department since last year, would replace Nikki R. Haley, who is stepping down as ambassador at the end of the year. If confirmed, Ms. Nauert would be one of the most prominent promoters of Mr. Trump’s “America First” foreign policy.

Ms. Nauert had been the favorite after Ms. Haley announced that she would leave the job, but after The Wall Street Journal reported that she was expected to be given the role, Mr. Trump grew muted about the choice, and administration officials said that she had become less interested in the post.

The president floated other names to associates as possible nominees, including Kelly Craft, the ambassador to Canada; Richard Grenell, the ambassador to Germany; and John James, a Republican who lost a Senate race last month in Michigan. At one point, Mr. Trump even signaled to Mr. James that the job was likely to go to him, according to one person familiar with the situation.