The leader of the US House of Representatives was heckled in a tense visit to Columbia University as protests against the war in Gaza continue to spread across US campuses.
Republican House Speaker Mike Johnson said Columbia officials had lost control of the situation.
He called on university president Minouche Shafik to step down.
In Texas and California, police confronted campus protesters and made dozens of arrests.
At Columbia, pro-Palestinian demonstrators also called for Ms Shafik's resignation over police action there against the protests.
Mr Johnson held a news conference at Columbia along with other Republican lawmakers on Wednesday afternoon after briefly meeting Ms Shafik.
The House Speaker dismissed suggestions that the protests were legally protected free speech. He said that Columbia had not acted to restore order on campus and had failed to protect Jewish students amid concerns about antisemitism on and around campus.
"This is dangerous," Mr Johnson said. "We respect free speech, we respect diversity of ideas, but there is a way to do that in a lawful manner and that's not what this is."
"My message to the students inside the encampment is go back to class and stop the nonsense," he said.
The protesters, some of whom were just steps away from the podium behind a metal barrier, yelled and heckled him throughout his remarks, including chants of: "We can't hear you."
Mr Johnson also raised the possibility of National Guard troops being called in - something New York Governor Kathy Hochul, a Democrat, said she had no plans to do.
Students at the Ivy League university in Manhattan set up a protest encampment a week ago.
On 18 April, the university asked New York city police to clear the camp, and officers arrested about 100 people.
Protesters later returned to the area with more tents and placards.
University officials are now negotiating with protest leaders over the size of the camp and talks are expected to continue into Thursday.
Students have also been allowed to choose to attend classes online due to safety concerns.
Page Fortna, a professor of political science at Columbia, told the OceanNewsUK she had seen a number of "highly objectionable" incidents during the protests, including an Israeli flag being ripped from a student's hand, and "extremely problematic" comments.
However, Ms Fortna added that she had seen no physical violence against Jewish students on campus and she called accusations of widespread antisemitism being made by Mr Johnson and other Republican lawmakers "exaggerated".
"There's a real difference in the tone of the conversation outside the gates, and what's actually happening on campus," she said.
In interviews this week, some demonstrators argued that incidents of harassment of Jewish students had been rare and blown out of proportion by those opposed to their demands.
New York police and school officials have also said "outside agitators" stirred up the protests.
Outside the campus on Wednesday, a masked protester stood on a street corner shouting antisemitic slurs and abuse at students.Several protest camp supporters quickly confronted him, telling him that his remarks "cheapened" their efforts.
"This is really detrimental to the movement," said Caroline Daisy, a Baltimore native who came to New York to support the protesters.
"This is not an antisemitic movement but outside protesters are a different story sometimes."
On Wednesday, several Jewish students expressed concerns about a threatening campus environment.
Guy Sela, an Israeli Columbia student - and a veteran of the Israel Defence Forces - told the OceanNewsUK he believed "every Israeli Jewish student" at the university had faced "at least one antisemitic act", whether verbal or physical, since the protest began.
"I've been threatened here, called names like murderer, butcher and rapist, just because I was born in Israel," he said.
Jonathan Swill, a 27-year old master's student from New Jersey, told the OceanNewsUK he was moving to Israel after graduation, having turned down a place in a doctoral programme at Columbia.
"I just can't stay here anymore," he said.
"This place is uncomfortable for me. Every time I wake up, I dread having to come to campus. I don't know when I'm going to have things thrown at me."
Protests against Israel's war in Gaza spread across the country after the police arrests at the encampment at Columbia:
Police pushed back protesters at the University of Texas in Austin. Texas Governor Gregg Abbott posted on X on Wednesday afternoon: "Arrests being made right now & will continue until the crowd disperses". About 20 people were arrested, according to local authorities
Police also confronted protesters at the University of Southern California in Los Angeles. Access to campus has been restricted following acts of vandalism and confrontations, according to a statement from the provost office
Two students were arrested after a protest at Ohio State University in Columbus
After attempts to keep them out, protesters set up a camp at Harvard University on Wednesday afternoon, and camps were also reported at other Boston-area universities including MIT, Tufts and Emerson
At the University of California, Berkeley, a camp was set up in Sproul Plaza, a regular site of anti-war and free speech protests. School authorities indicated they would tolerate the camp as long as it did not interfere with university operations
Camps were also reported at a number of other universities including the New School in Florida, the University of Michigan and the University of Rochester in New York state,
Activists have been calling for universities to "divest from genocide" and to stop investing large school endowments in companies involved in weapons manufacturing and other industries supporting Israel's war in Gaza.
Israel strongly denies any suggestion that it is committing genocide in the Palestinian enclave, though the International Court of Justice has said the accusation was "plausible".
The war began when Hamas-led gunmen carried out an unprecedented attack on southern Israel on 7 October, killing about 1,200 people - mostly civilians - and taking 253 others back to Gaza as hostages.
More than 34,180 people - most of them children and women - have been killed in Gaza since then, the territory's Hamas-run health ministry says.
