Trump is playing up the recommendations of his former rivals. Haley has Judge Judy.

As former President Donald J. Trump enlists a number of former rivals to help him make closing arguments for the New Hampshire primary, Nikki Haley, his last remaining Republican opponent, has approached a different kind of bench: Judge Judy.

Television's best-known judge, whose real name is Judith Sheindlin, waded into the race on Sunday as she campaigned for Ms. Haley at the Exeter, N.H., rally, albeit without her trademark gavel and robes.

It was a rare foray into presidential politics for Ms. Sheindlin, who narrated it CNN Sunday that Mrs. Haley had made a strong impression on her.

She pointed out that she did not support Ms. Haley, the former governor of South Carolina and Trump's ambassador to the United Nations, simply because she was a woman.

“I would support her if she were a frog,” said Ms. Sheindlin, who supported Michael R. Bloomberg, the former New York mayor, during his unsuccessful run in the 2020 Democratic primary.

Ms. Sheindlin avoided attacking Mr. Trump, the Republican front-runner, but she said he was too distracted with his criminal and civil cases to focus on governing.

The television star argued that Mr. Trump and President Biden's ages were catching up with them and that “they wouldn't be able to tell a Houthi from a salami,” referring to the Iran-backed militia in power in Yemen and a meat shop.

She said that even she — at 81, the same age as Mr. Biden — has not been able to turn back time.

“I need a nap in the afternoon,” said Mrs. Sheindlin. “That includes Joe Biden, probably two.”