A star New York Magazine political reporter has been placed on leave after disclosing a personal relationship with the former presidential candidate Robert F. Kennedy Jr.

In a statement posted online on Thursday night, New York Magazine said that its Washington correspondent, Olivia Nuzzi, had recently acknowledged to the magazine’s editors that she had engaged in a relationship “with a former subject relevant to the 2024 campaign while she was reporting on the campaign.” The outlet said the relationship was “a violation of the magazine’s standards around conflicts of interest and disclosures.”

A person familiar with the matter confirmed that the relationship was with Mr. Kennedy, a former Democrat who ended his independent run for president in August and has since endorsed former President Donald J. Trump. Mr. Trump’s campaign has named Mr. Kennedy to his transition team should he win the election in November.

New York Magazine said on Thursday that it had reviewed Ms. Nuzzi’s work and found “no inaccuracies nor evidence of bias.”

“She is currently on leave from the magazine, and the magazine is conducting a more thorough third-party review,” the publication said.

David Haskell, the editor of New York magazine, said in a note to staff on Friday that Ms. Nuzzi had told editors about the relationship a few days ago. She told them that it had started in December 2023 and ended in August.