Ms. Nuzzi told her editors about the relationship that had turned personal, the outlet said. A representative for Mr. Kennedy said the pair had met only once.

"Had the magazine been aware of this relationship, she would not have continued to cover the presidential campaign," New York magazine said in a statement.

One of America’s most acclaimed magazine writers, Olivia Nuzzi of New York magazine, has been placed on leave while a “third-party review” is conducted after Nuzzi disclosed that she “had engaged in a personal relationship with a former subject relevant to the 2024 campaign while she was reporting on the campaign.