Conservative firebrand Ann Coulter on Wednesday canceled a planned appearance at the University of California, Berkeley, saying she had lost the backing of the groups that had sponsored her talk.
"It's a sad day for free speech," Coulter told the New York Times.
The right-wing commentator had insisted she would show up at Berkeley, a famously progressive campus, on Thursday even though the university said it could not provide a suitable venue because of security threats.
But Coulter said she was forced to reconsider her decision after the conservative Young America's Foundation and the Berkeley College Republicans, which had sponsored her talk, backed out, accusing the university of creating a "hostile atmosphere."
"Everyone who should believe in free speech fought against it or ran away," Coulter told the Times.
The controversy over her talk put the spotlight on the San Francisco-area university long heralded as the birthplace of the Free Speech Movement of the 1960s.
University officials have insisted that security could not be guaranteed during Coulter's visit, citing threats and recent violent protests.
They proposed an alternate date -- rejected by Coulter -- when fewer students would be on campus.
She is a conservative firebrand, author, attorney and political commentator. She is famous for blunt attacks on those who don't share her views.
Her 2015 tome on immigration was called "¡Adios, America!: The Left's Plan to Turn Our Country Into a Third World Hellhole."
- 'University not a battlefield' -
Berkeley Chancellor Nicholas Dirks underlined in a letter to the campus community on Wednesday that the university was committed to free speech but also to safety.
"Sadly and unfortunately, concern for student safety seems to be in short supply in certain quarters," he said.
"This is a university, not a battlefield," he added. "We must make every effort to hold events at a time and location that maximizes the chances that First Amendment rights can be successfully exercised and that community members can be protected."
In February, a planned speech at the university by a right-wing provocateur and former Breitbart editor, Milo Yiannopoulos, was cancelled following violent protests that caused $100,000 worth of damage to the campus.
Violence has also erupted on the streets of the city during recent events that drew opponents and supporters of President Donald Trump.
The latest controversy surrounding Coulter's visit has tested Berkeley's legacy as a champion of free speech and elicited criticism from both Democrats and Republicans.
Many say the university was being targeted by extremists from the far right and left because of its iconic status.
Liberal TV talk-show host Bill Maher said last week the school had turned from being a cradle of free speech into a "cradle of (expletive) babies."
Ex-presidential contender Bernie Sanders also waded in, denouncing activists trying to silence Coulter.
"Obviously Ann Coulter is outrageous -- to my mind, off the wall," he told the Huffington Post. "But you know, people have a right to give their two cents worth, give a speech, without fear of violence and intimidation."
The American Civil Liberties Union said Wednesday the cancellation of her talk marked a setback.
"The heckler's veto of Coulter's Berkeley speech is a loss for the 1st Amendment," the rights group tweeted. "We must protect speech on campus, even hateful."