NEW YORK — Pam Bondi, the former Florida attorney general, was chosen by Donald Trump to serve as U.S. attorney general hours after his first choice, Matt Gaetz, withdrew from consideration after a federal sex trafficking investigation and ethics probe made his ability to be confirmed dubious.

In Ms. Bondi, who served on his legal team during his first impeachment, the president-elect turned to a loyal ally to put his stamp on a Justice Department that he sees as hostile to him.