While Nikki Haley has, until recently, run a fairly positive campaign, she has endured relentless criticism from Donald J. Trump and others in his orbit. Her 22-year-old son, Nalin Haley, is not so inclined to pull his punches.

Mr. Haley, who has become a more familiar presence on the trail with his mother, introduced her at events over the weekend, taking some pointed jabs at her onetime Republican rivals.

He has a nickname for Senator Tim Scott: Senator Judas. Another former rival who went full-bore for Mr. Trump, Vivek Ramaswamy, draws Mr. Haley’s comparisons (derogatory) to Pennywise, the clown from “It.”

Ms. Haley, for her part, has been deferential: At one event she ran through “thank you’s” for the other speakers before jokingly saying, “Nalin, I will deal with you later.”

On Saturday, while introducing his mother in Gilbert, S.C., he acknowledged that he was in “the state that raised me,” and “the state that took a chance on my mom.” The current moment, he said, was “like history repeating itself — it feels like 2004, 2010, where the establishment is up against her,” he said.

Then, he got personal.

“We had a lot of them go up to New Hampshire, and I saw Trump standing side by side, he was next to Senator Judas — excuse me, Senator Scott,” he said to “oohs” from the audience. “Ouch,” someone in the crowd said.