Three speakers backed out of a far-right rally planned for this weekend on Boston Common, casting doubt on the event amid strong opposition from city and state officials fearful about a repeat of the bloodshed in Charlottesville, Va.

In a show of resolve, Mayor Martin J. Walsh joined Governor Charlie Baker, other elected officials, and civil rights leaders on City Hall Plaza Monday afternoon to denounce the hate and white nationalism that authorities said fueled the violence in Charlottesville, where a woman died Saturday after an Ohio man allegedly drove his car into the crowd.

Walsh vowed to do everything possible “so that the march or this demonstration does not happen in our city,’’ while other city officials said that if the rally proceeded they would keep participants safe.

Baker said that anyone caught in acts of violence would be held accountable.

“What happened in Virginia was a tragedy and an act of terror,’’ Baker said. “I want to be clear that there is no place here for that type of hatred.’’

Tanisha Sullivan, head of the local NAACP, said the city is sending a clear message that “we stand against hatred, racism, and the terrorism that we all witnessed over the weekend.’’

Some of the speakers seemed to have received the message that they were not welcome in Boston.

Augustus Invictus, an Orlando activist who took part in the Charlottesville rally, said organizers of Boston’s rally texted him on Monday and said it was necessary to cancel “from a PR standpoint,’’ after Saturday’s violence in Virginia.

Invictus, who attracted support from white supremacists when he ran for the US Senate as a Libertarian in Florida in 2016, said organizers indicated they were also worried about statements he has made espousing support for a “second American civil war.’’

Another planned headliner, Gavin McInnes, said he was backing out. McInnes, who heads a group of self-described “Western chauvinists’’ called the Proud Boys, accused Walsh and other city officials of trying to incite a riot to discredit the assortment of right-wing activists who planned to rally in Boston.

“It’s a trap!’’ McInnes tweeted. And in an e-mail to the Globe, he added: “I’m out.’’

A third speaker, Cassandra Fairbanks, tweeted that she also was not going to speak at the rally. “The threats keep escalating and people are unhinged rn,’’ she wrote, using Internet shorthand for “right now.’’

City Councilor Tito Jackson, who is running for mayor, urged unity in a statement and vowed to resist the spread of hate.

At Monday’s press conference, authorities said they were trying to learn more about the rally, including who the organizers are and whether it would proceed as advertised on social media.

Robert Trestan, executive director of the Anti-Defamation League’s Boston office, said the event is part of a new movement called the “alt-lite,’’ which he described as a “broader effort among some right-wing people and groups to bring their ideological battles into the streets.’’

The groups reject the white supremacism and racism of the “alt-right’’ that gained currency with the election of President Trump, he said, but still “appeal to classic forms of bigotry, misogyny, and anti-Semitism and Islamophobia.’’

“There should be no mistake that they traffic in hatred and disseminate messages of hatred,’’ he said.

As of Monday evening, members of a group that calls itself the New Free Speech Movement said the rally would continue.

Alexander Sender, a 23-year-old Cambridge resident, said he had applied for a city permit to hold the event, and records show he began the process on the city’s special events online portal. But city officials said that organizers have not applied to the Parks Department, which issues permits for large-scale events and is the key step to holding rallies in Boston’s public spaces.

Sender told the Globe that he was not aware there was one more step in the application process and said he will contact city officials to ensure the event is properly permitted.

“We want to follow the rules,’’ he added, reiterating the event will happen.

US Senate candidate Shiva Ayyadurai, who said he was scheduled to speak Saturday, said if the rally happens, “I will be there. If it doesn’t happen, I won’t be there.’’ Ayyadurai, one of several Republicans seeking to challenge US Senator Elizabeth Warren next year, added that he aims to support free speech, and “I’ve been fighting white supremacism and racism all my life.’’

Another speaker, Joe Biggs, who lives in Austin, Texas, said he was still planning to travel to Boston for the rally, despite the cancellations.

“If 10,000 lefties murder me, then so be it,’’ he said in an interview. A former Army staff sergeant, Biggs worked until recently for Infowars, a website founded by Alex Jones, the conspiracy theorist.

Biggs was among those promoting the Pizzagate conspiracy theory, which falsely claimed a pedophile ring with links to Hillary Clinton was operating out of a Washington, D.C., pizzeria.

In an interview, Biggs insisted the rally in Boston is designed to promote free speech — not hate or violence. “These events are not violent in nature at all but people will defend themselves if provoked, and that’s what happened in Charlottesville,’’ he said.

He disavowed any support for racists, saying: “My wife is Guyanese. I have a mixed baby. I’m the furthest thing from a [expletive] Nazi.’’

But in a video posted on his Twitter feed on Saturday, he talked positively about the message of the Charlottesville rally. “There’s nothing wrong with white people wanting to preserve their race,’’ he said. “There’s nothing wrong with white people bring proud of being white.’’

Another scheduled speaker, Kyle Chapman, gained notoriety earlier this year after a video went viral of him smashing a wooden post over the head of an anti-fascist protester at a march for President Trump in Berkeley, Calif.

Chapman, who became known on the Internet as Based Stickman, then started a group called the Fraternal Order of Alt Knights, which the Southern Poverty Law Center describes as a “New Alt Right Fight Club ready for street violence.’’ Chapman, who lives in California, did not return messages on Monday.

Although speakers affiliated with the Boston rally have sought to distance themselves from the white supremacists who marched in Charlottesville, many espouse similar beliefs in white pride, hatred of Islam, and support for Trump.

The city has little recourse if the group holds the rally without a permit: People can lawfully assemble and participate in free speech — actions that do not require a permit.

Walsh said he would encourage the rally organizers to postpone their event at a time of high emotion in the wake of Charlottesville. “We would probably ask them not to come to our city at all’’ this weekend, Walsh said. “Boston does not welcome you here, Boston does not want you here, Boston rejects your message.’’

Police Commissioner William B. Evans said that if a rally does happen, his officers will keep that rally apart from any counterprotesters.

“We’ve handled major demonstrations, and I don’t find this any different,’’ he said. “It’s pretty sad that we have to waste so many resources on such a group . . . with such hatred coming to Massachusetts.’’

Evans said organizers planning the rally are not the same as the oneswho held a free-speech rally on the Common in May, which drew counterprotesters and clashes, he said.

Irons can be reached at meghan.irons@globe.com.