After the presidential election, he saluted an audience of more than 200 at the National Policy Institute’s annual conference in Washington with the cry “Hail Trump, hail our people, hail victory!” In response, a number of his supporters gave the Nazi salute.

In May Mr. Spencer, a University of Virginia graduate, led a torch-bearing group in Charlottesville to a statue of Robert E. Lee, the confederate general, that the city wanted to remove. They chanted, “You will not replace us,” and “Blood and soil.” That dispute led to a bigger “Unite the Right” rally in Charlottesville in August, which erupted into street violence, leaving one woman dead when a car driven by a man associated with white supremacist groups plowed into a crowd.

Mr. Spencer appeared again in Charlottesville on Oct. 7 at a small torch-lit rally. He did not return a phone call seeking comment on his visit to the University of Florida.

Why will the college let him speak?

After the university denied Mr. Spencer’s original request, a local lawyer, Gary Edinger, threatened to sue on First Amendment grounds. Mr. Edinger, a First Amendment lawyer, said in an interview Tuesday that he had taken the case pro bono. His views do not match Mr. Spencer’s, he said, adding that he had voted for Bernie Sanders because he wanted a socialist for president.

The university responded to the lawsuit threat by saying that the ban was not supposed to be permanent, and then negotiated conditions of Mr. Spencer’s appearance with Mr. Edinger, said Janine Sikes, a spokeswoman for the university.

“Essentially the university opted to agree on a future date that gave us time to plan for safety and security, and certainly have some say in other factors leading to the event, making it during the daytime, for example,” Ms. Sikes said. Some colleges ask polarizing speakers to appear during the day to make crowd control easier.

As a public institution, the University of Florida cannot choose speakers based on their point of view, First Amendment experts say.