The University of California at Berkeley is bracing for massive protests and potential violence in an open, public space known as Sproul Plaza after learning that conservative commentator Ann Coulter plans to give a Speech there Thursday afternoon.

The state flagship university has become ground zero for an intense confrontation between the far left and the far right since Donald Trump’s election in November, with some protesters trying to stop controversial speakers from appearing on Campus and others objecting that such actions violate their right to free speech. Some of the clashes have devolved into riots, leaving the school and city to struggle with how best to balance the free exchange of ideas with community safety.

In February — and twice more since then — masked protesters turned demonstrations over the boundary between free speech and hate speech into violent confrontations, setting fires, causing injuries and leaving hundreds of thousands of dollars of property damage in their wake.

“The character of that attack on campus was unprecedented,” UC-Berkeley chancellor Nicholas Dirks said Tuesday.

Coulter’s choice of Sproul Plaza, site of the Free Speech Movement protests in the 1960s, is both symbolic and logistically challenging for the university because anyone can be there. Dirks said that for an inside event, the university would have metal detectors and other ways to search for weapons, but security will be much more difficult in a public outdoor space.

“If somebody brings weapons, there’s no way to block off the site, or to screen them,” Dirks said, noting that officials know that some of the demonstrators, such as those known as Black Bloc, know how to penetrate the crowd and use it as a shield. “In an open space, you have almost no control over that,” he said. “The challenges are immense.”

After the university went on lockdown after a February clash and police urged university officials to cancel controversial writer Milo Yiannopoulos’s speech — which they did — President Trump raised the threat of pulling federal funding from the public school.

But the cancellation of the Yiannopoulos event further galvanized activists on the far right, who viewed it as a call to arms and proof that conservatives around the country are being oppressed. And in recent weeks, rallies in the city of Berkeley have devolved into bloody street brawls. Left-wing activists have clashed with Trump supporters, and anarchists in black masks have squared off against self-proclaimed militia groups.

Coulter did not immediately respond to a request for comment on her planned appearance. On Monday she retweeted a weather forecast with this comment: “Nice day for an outdoor speech at Berkeley.”

Berkeley College Republicans originally invited Coulter to speak on campus Thursday, but university officials canceled the event because of safety concerns. The university, facing backlash, quickly reversed course and invited her to speak next week instead at an indoor location.

Coulter rejected that offer and said she still planned to come to Berkeley on Thursday despite the university’s warnings against it. On Monday, student groups filed a lawsuit against university officials, complaining that the university’s decision was stifling free speech at the school, particularly for politically conservative students whose views are controversial on the liberal campus.

“Though UC Berkeley promises its students an environment that promotes free debate and the free exchange of ideas,” the lawsuit contends, “it had breached this promise through the repressive actions of University administrators and campus police, who have systematically and intentionally suppressed constitutionally-protected expression” by the many students whose political views align with the plaintiffs.

The lawsuit claims that students typically leave campus in early May — the week known as “dead week” before final exams — and that delaying Coulter’s speech until then limits her potential impact. Dirks countered that claim.

“That’s not our experience,” he said. “It’s not a vacation. We assume students stay and work in the libraries.”

Having the event next week would open up options because there will be no conflict with classes and it would be much easier to get a safe venue, Dirks said. There were very few places police believe they can secure for such a speech given the current climate, he said.

Dirks defended the university’s commitment to free speech and said his concerns about academic freedom include worries about some members of the College Republicans who have been targeted by other members of campus for their views.

In his time as chancellor, protesters tried to stop liberal television host and comedian Bill Maher from speaking, but Dirks said he insisted that Maher come. He told students and faculty upset about Yiannopoulos that his First Amendment rights should prevail over their concerns that he violates the community’s values.

University officials thought they were prepared for Yiannopoulos, having erected three barrier chain-link fences, placed about 90 police officers on campus, and searched for weapons and other items when ticket-holders came inside. But that wasn’t enough.

“It took about 15 minutes for Black Bloc protesters to come and begin to break the windows and doors … and light a major fire using a propane tank that was there for temporary lighting,” Dirks said.

The campus has become a symbolic center of a much larger fight, he said, with a growing perception among many that universities are so steeped in political correctness that they reject real debate, that they are isolated bubbles with values antithetical to the Trump administration. But they also face anger from the far left for allowing speakers whose views offend some. “We’re getting hit from both sides,” Dirks said.

Since February, he said, “We’re engaged in a new reality — what was unprecedented is not going away.” Now people think of the campus as a place “for the mounting of pitched battle, and the staging of violent controversies.”

Dirks said Tuesday that, given the school’s history, “It is in a way fitting that Berkeley be a leader in helping figure out how the new political realities are going to affect the life of the university.”

It’s not just a problem at Berkeley.

Last week at Auburn University, a fistfight broke out during protests when alt-right leader Richard Spencer spoke on campus. Earlier this year at Middlebury College, an angry mob of hundreds surrounded author and conservative scholar Charles Murray after he tried to give a lecture about his most recent book. Protesters, including some wearing masks, climbed on the hood of his car and pounded on windows as he tried to leave.

Lawrence Lokman, a spokesman for Penn State University, confirmed that its president, Eric Barron, serves on “an academic advisory committee to Homeland Security and co-chairs a subcommittee on countering extreme violence on campuses. As part of that, they have received a briefing on violence related to campus speakers.”

Pranav Jandhyala, who leads one of the two student groups that invited Coulter, said Tuesday that Coulter told him and other students that she plans to speak Thursday afternoon at Sproul Plaza.

Jandhyala said his student group has been trying frantically to find an off-campus venue for Thursday, and he said he shares the concerns of university officials that Coulter’s appearance at Sproul — and the protests and counter-protests it likely will spark — could grow violent. But he said that Coulter made clear in communication with him and other student organizers on Tuesday morning that she intends to go through with her plan to appear at the public plaza.

“We’re worried about it turning into a huge battle between her security and conservative militia and antifascists and others,” Jandhyala said. “To have that right in the middle of Sproul doesn’t bode well for the image of our school or the city. We’re worried about violence and student safety and our own safety as well. It’s a huge safety concern.”

He said the exact time of Coulter’s speech is still uncertain, but he expects it likely will be at about 4 p.m. “She said she doesn’t even know her full schedule on Thursday right now. She’s going to know Thursday morning and relay to us when she plans to come to Sproul,” Jandhyala said.

When Jandhyala’s group, the politically moderate Bridges USA, teamed up with Berkeley’s College Republicans to invite Coulter to campus, the goal was to facilitate a dialogue about immigration.

“It’s an issue that hits home for many of our students,” Jandhyala said. “Berkeley is a sanctuary city. We have many undocumented immigrant students. That’s why it seemed like a good issue to put on the table. UC-Berkeley can represent the liberal point of view very well. So what we were trying to do with Coulter was to bring in an opposing view to have a dialogue about it.”

While that was the original purpose, Jandhyala acknowledged that Coulter might now have a different agenda for her appearance: “Her goal is testing the limits of speech and doing all she can to uphold this value and prove what’s possible and not back down from free speech.”

Her outdoor speech at the plaza likely will make it difficult for any dialogue or interaction with students, he said, and his group is trying to have a separate event with her that would allow for conversation.

Dan Mogulof, a university spokesman, said the school does not discuss security arrangements in detail, but he said officials will take extraordinary steps to protect the campus, in coordination with local and regional law enforcement.

“At UC-Berkeley, we don’t have gates,” Mogulof said. “There are probably literally hundreds of ways to come onto campus from the city. We don’t have a drawbridge or moat. We are a completely porous campus.”

Dirks had a message for extremists: “I’d like to ask them to stay away. It’s a college campus. If they want to come and engage in free speech, that’s great. If they want to come and disrupt and engage in other activities, they should stay away from the university.”