Karoline Leavitt, a 27-year-old New Hampshire native, will have one of the most visible jobs in the new Trump administration.

Biden officials harbor deep worries in particular about the fate of their work abroad, where Trump is expected to abruptly shift the U.S.' priorities. The administration is racing to ship a last batch of aid to Ukraine before Jan. 20, for fear Trump will immediately cut off support for the country’s defense against Russia.