Rightwing activists in Portland, Oregon, appear to have shifted tactics in their ongoing confrontation with leftwing groups and city authorities, attempting forced “demaskings” of opponents and picketing union venues and events. One activist has threatened the city’s mayor, Ted Wheeler.

Since the election of Donald Trump as president in 2016, the Vancouver, Washington-based Patriot Prayer group, led by the former Republican Senate candidate Joey Gibson, has staged frequent rallies in Portland. Opposed by leftwing counter-protesters, many such events have become violent.

Wheeler has become a hate figure on the far right, ostensibly over the city’s response to a Portland protest in June 2018 that descended into a bloody riot. The mayor was among public figures threatened by Cesar Sayoc, the suspect in the so-called “Maga bomber” case.

Last week, Reggie Axtell, a member of the “western chauvinist” Proud Boys group and a frequent attendee at Patriot Prayer marches, issued a threat to Wheeler. In a video posted to Facebook, Axtell said the mayor’s “days are fucking numbered” and added: “I promise you this, Ted Wheeler: I’m coming for you, you little punk.”

Axtell also said he would try to “unmask every antifa son of a bitch that I come across” and said: “Like Joey Gibson says, behind every blade of grass there is a gun.”

Gibson has said Patriot Prayer will seek to occupy the grounds of Wheeler’s house, to protest against homelessness in Portland. Patriot Prayer member Haley Adams, who organized an anti-#MeToo march in Portland late last year, has been promoting a recall campaign against the Portland mayor.

Responding to the Guardian, a spokesman for Wheeler attributed national attention and the “routine threats” the mayor receives from around the US to his being “a symbol of progressive values that [the far right] don’t share”. The Portland police bureau did not respond to questions about the threat.

Axtell did not respond to requests for comment. Gibson denied that Axtell threatened Wheeler’s safety, saying he instead “threatened his job”, but conceded that he had not watched the video closely.

In a video posted to the Patriot Prayer Facebook page on Saturday evening, meanwhile, Gibson and Vancouver resident Steve Drury are seen approaching a young man wearing a white face mask and part of a leftwing group protesting at an Immigration and Customs Enforcement (Ice) facility that was the site of protests last summer.

Drury is seen to grab the protester from behind; Gibson pulls down his mask. Videos taken by other attendees show the incident from other angles.

A Facebook comment accompanying the original video read: “Demasking Portland Antifa. Many people voluntarily took their masks off the minute we showed up. We are on to something.” The comment linked to a fundraising site for Patriot Prayer.

On social media, Gibson and other Patriot Prayer members have advocated “demasking” counter-protesters. On Sunday, Gibson posted a video to his own Facebook page in which he defended what he described as an “increase in aggressive tactics” which he also said was “nonviolent”.

“I am following my heart,” he said. “These streets need to be cleaned up. And one of the simple and nonviolent ways we can do it is not allow masks at any event.”

Asked by the Guardian what would happen if people refused to remove their masks, Gibson said: “We’re gonna take them off.”

Asked if that meant he would use force, Gibson repeated that his group was “gonna take down the masks” and said: “We’re gonna take their picture.” He said this could be done nonviolently, then made a series of claims about violence among counter-protesters at his rallies.

The tactic, he said, was “a way to expose people. It makes it impossible for them to commit crimes.” Drury’s manhandling of the protester outside the Ice building was, he said, “unnecessary … but he definitely didn’t hurt him. It was a bear hug.”

“It would almost be to my advantage if [law enforcement] come after me for something like that,” he said, “because it would blow up. It would be national news and their hypocrisy would be exposed. If they want to charge me, bring it, I’m ready.”

Gibson also said “we’re gonna make [demasking] a national thing”.

In Portland, Patriot Prayer members have also attempted to force their way into leftist meetings, protested outside union halls and forced the cancellation of public lectures. Many such actions have been targeted at an Industrial Workers of the World (IWW) Hall in the east of the city, around events organized by the Democratic Socialists of America (DSA).

On Thursday 17 January, according to Willamette Week, members of Patriot Prayer were turned away from a DSA meeting at the IWW Hall, and became involved in a scuffle with a separate group nearby. On Saturday 19 January, Gibson led another protest outside the hall.

On Wednesday 23 January, the hall, a bar frequented by anarchists and a Democratic party building were vandalized by persons unknown. The vandalism included spray-painted anti-leftist slogans: “Antifa House” and “Smash Communism”.

Gibson denied responsibility, suggesting it was a “false flag” attack from “someone trying to get sympathy”. He admitted he had no evidence for that claim.

On Friday, Portland Community College cancelled a speech organized by Portland DSA after Patriot Prayer members said they would attend.

Asked about the video of the “demasking” incident at the Ice facility, a Portland police spokesman said: “The bureau views public videos on social media like any other organization, group, etc. These videos are then used to determine the proper course of action and resources that are needed relating to any planned or unplanned event.”

Police said they were investigating the vandalism.