Getting out in front of a planned demonstration and counter-demonstration by the far-right group Patriot Prayer and anitfa, the Portland Police Bureau Friday released details of what they plan to do and what demonstrators should not do, CBS Portland affiliate KOIN reports. Police told protesters to leave their guns at home, and warned there will be "a significant law enforcement presence in the area of the demonstration due to past threats and acts of violence."

Portland is bracing for what could be another round of violent clashes between a right-wing group and self-described anti-fascist counterprotesters who have pledged to keep Patriot Prayer and other affiliated groups out of the city.

Joey Gibson, the leader of Patriot Prayer and an announced Republican U.S. Senate candidate in Tuesday's Washington primary, said Monday every attendee should "be carrying around guns at all times -- especially people in our situation," KOIN reports.

Get Breaking News Delivered to Your Inbox

Gibson said they've hired armed guards to accompany protesters to the rally, but he said Friday he will not have a gun at the rally.

Saturday's planned rally was expected to be the third to roil Portland this summer. Two previous events ended in bloody fistfights and riots, and one counterprotester was sent to the hospital with a skull fracture.

This time, Gibson changed the venue from a federal plaza outside U.S. District Court to a waterfront park so his supporters can carry concealed weapons as they demonstrate. Chartered buses will bring participants from Vancouver, Washington - where Gibson lives - to downtown Portland with armed security on board.

Gibson's insistence on bringing his right-wing supporters repeatedly to this blue city has crystallized a debate about the limits of free speech in an era of stark political division. Patriot Prayer also has held rallies in many other cities around the U.S. West, including Berkeley, California, that have drawn violent reactions.

But the Portland events have taken on outsized significance after a Patriot Prayer sympathizer was charged with fatally stabbing two men who came to the defense of two young black women - one in a hijab - whom the attacker was accused of harassing on a light-rail train in May 2017.

A coalition of community organizations and a group representing more than 50 tribes warned of the potential for even greater violence than previous rallies if participants carry guns. It called on officials to denounce what it called "the racist and sexist violence of Patriot Prayer and Proud Boys" and protect the city.

Portland police say they will be checking for weapons to ensure anyone who is armed has an Oregon concealed handgun license.

Gibson, who is running a long-shot campaign to unseat Democratic U.S. Sen. Maria Cantwell of Washington state, said in a live video on Facebook earlier this week that he won't stop bringing his followers to Portland until they can express their right-wing views without interference.

"I refuse to do what Portland wants me to do because what Portland wants me to do is to shut up and never show up again. So yeah, I refuse to do that, but I will not stop going in, and I will not stop pushing, and I will not stop marching until the people of Portland realize that and realize that their methods do not work," he said.

Self-described anti-fascists - or "antifa" - have been organizing anonymously online to confront Patriot Prayer and an affiliated group, the Proud Boys, in the streets.

A broader counterprotest organized by a coalition of labor unions, immigrant rights groups and artists also will gather at City Hall before the Patriot Prayer rally. Organizers say that while Patriot Prayer denies being a white supremacist group, it affiliates itself with known white supremacists, white nationalists and neo-Nazi gangs.

"Patriot Prayer is continuing to commit violence in our city, and their events are becoming more and more violent," said Effie Baum of Pop Mob, a coalition of community groups organizing the counterdemonstration. "Leaving them a small group to attack in the streets is only going to allow them to perpetuate their violence."

Dueling protests a month ago ended with Portland police declaring a riot and arresting four people. A similar Patriot Prayer event on June 4 devolved into fistfights and assaults by both sides as police struggled to keep the groups apart.

The man charged in last year's light-rail stabbing deaths, Jeremy Christian, was filmed making the Nazi salute at a Patriot Prayer rally a month before the killings.

Christian, who has pleaded not guilty, later told investigators he was not motivated by racism but was drunk and wanted to "do his free speech thing" when he shouted racist and anti-immigrant slurs on the light-trail train before the stabbings.

In the aftermath, Gibson organized a pro-President Donald Trump free speech rally that attracted thousands from both sides to downtown Portland. The ensuing chaos shut down much of the city's core and police arrested more than a dozen people amid widespread fighting.