In response, Mr. Gordon began to walk closer to her. Ms. Manigault-Newman, who had been seated, stood up and walked across the stage and said Mr. Gordon was being “aggressive.”

She also accused the crowd of journalists of not having sympathy for the deaths of her father and brother. “I came out to laughter as if this was a joke,” she said. “Walking into a room where you get shut down does not open a line of communication so change can happen.”

At one point, Ms. Manigault-Newman accused Mr. Gordon of brushing aside her relatives’ deaths. When Mr. Gordon said she was wrong, she replied, “I have it on tape, boo.” His response: “O.K., boo, play it.”

Mr. Gordon also asked Ms. Manigault-Newman about what she told the president after his remarks on Long Island. Ms. Manigault-Newman said she could not “disclose confidential conversations with the president,” which led to loud sighing and snickering in the crowd, though Ms. Manigault-Newman did say she thought it was wrong for Mr. Trump to make those comments.

She later said she had invited several law enforcement officials to come to the White House to discuss criminal justice issues. But at one point, asked how she worked with the Justice Department on issues of policing, Ms. Manigault-Newman suggested that people in the room should “Google” her work. Pressed about the topic later, she added, “It’s not even part of my portfolio.”

“I’m not going to stand here and defend everything about Donald Trump,” she said, to loud sighs in the audience.

Heading into the forum, many of the conference attendees said they were steeling themselves for the appearance of Ms. Manigault-Newman, who became famous on “The Apprentice” and has had several fiery exchanges with journalists. Several journalists who were scheduled to be on the panel pulled out of the event after Ms. Manigault-Newman was added.