Mr. Semans, a member of the Rosebud Sioux Tribe, faulted President Trump for repeatedly calling Ms. Warren “Pocahontas.” He said he had no problem with how Ms. Warren had referred to her ancestry, and that it was more important to spend time on issues that could help the lives of Native Americans, “not whether or not her DNA test was done properly or improperly.”

“How many times do you have to argue something that’s already done?” he asked. “That issue has been dealt with, it’s been taken care of, and we move on. But what hasn’t been dealt with and taken care of is President Trump’s continued use of it in a derogatory way.”

One of the panelists during Ms. Warren’s appearance, Aaron A. Payment, the chairman of the Sault Ste. Marie Tribe of Chippewa Indians, recalled a conversation with Ms. Warren in 2013 in which she discussed her heritage on “a very personal level.”

“I urged you to tell your story, and I appreciate that you did,” he said. “What I would say is, from here forward, because now we’re in a presidential election, that we take Michelle Obama’s advice and when he goes low, you go high.”

It remains to be seen how much the ancestry issue will linger over Ms. Warren as the campaign goes on. At a rally in New Hampshire last week, Mr. Trump repeated the “Pocahontas” slur and promised there would be more to come.

“I did the Pocahontas thing,” he said. “I hit her really hard, and it looked like she was down and out, but that was too long ago. I should have waited. But don’t worry, we will revive it.”

Everett Baxter Jr., 34, a tribal leader for the Omaha Tribe of Nebraska who attended the forum, said he believed there was no need for Ms. Warren to apologize.