PHOENIX — As the board of supervisors for Arizona’s largest county abruptly ended a meeting late last month, a swarm of people rushed toward the dais, shouting that the members were illegitimate.

The Maricopa County leaders made a beeline for a side door and were swiftly escorted out of the chamber by security guards, who called for backup from the sheriff’s office. After the meeting’s live-feed went dead, a member of the crowd yelled that a “revolution” was underway.

“I’m here today to put you on public notice and to inform you that you are not our elected officials,” said Michelle Klann, co-founder of a pro-Trump group, from a podium she had commandeered. “This is an act of insurrection. Due to all the voter fraud, you have never been formally voted in.”

The scene at the Feb. 28 meeting terrified many Maricopa employees and others who were reminded of what happened after Joe Biden won the county — and, with it, Arizona — in the 2020 presidential race. Back then, Trump supporters used baseless fraud claims to try to pressure or scare elected leaders into changing the results for the metro Phoenix county, which is home to more than half of Arizona’s residents.

Now, with another presidential election quickly approaching and Arizona again likely to be central to Donald Trump’s electoral strategy, the incident late last month has revived fears that officials responsible for running Maricopa County elections will be targeted with a campaign of threats and abuse — or worse.

“This was an organized, coordinated attack,” said one top county official who spoke on the condition of anonymity to discuss sensitive security matters. “It was a dress rehearsal for the election.”

Since the 2020 vote, the Maricopa supervisors — most of whom are Republicans — have faced relentless public ridicule, conspiracy theories and death threats for signing off on the results and refusing to go along with Trump’s efforts to overturn the outcome.

Trump’s razor-thin loss of the state — a mere 10,457 votes of nearly 3.4 million cast — thrust its most important battleground county into the heart of national efforts to undermine confidence in elections.

Arizona voters in 2022 narrowly defeated Republican candidates for governor and other statewide offices who made election denialism a centerpiece of their campaigns. The issue remains a major animating force for the state’s GOP, and Republican lawmakers have even gone so far as to try to break up Maricopa in a move widely seen as retribution for the county’s role in Trump’s defeat.

Maricopa supervisors have become accustomed to the crowds of people who heckle and disparage them in public meetings, a tactic that has played out since the 2020 vote in localities around the nation, from California to Texas. In response to escalating disruptions, Maricopa officials have recently become more aggressive in ordering out unruly attendees or adjourning sessions early to try to avoid viral confrontations.

But the chaotic ending to last month’s meeting marked for some a new level of menace — one reminiscent of the tone preceding the Jan. 6, 2021, attack on the U.S. Capitol — and illustrated the lengths to which Trump’s supporters are willing to go in disrupting public proceedings. Trump’s fraud claims were debunked long ago, but his most ardent backers remain unconvinced.

“There are people who have believed those messages — as false as they are — and are believing that they need to take action,” said Tammy Patrick, the chief executive for programs at the National Association of Election Officials.

In the case of last month’s meeting, the action taken ended peacefully. Outnumbered, the county’s security staff waited for sheriff’s deputies as they calmly ushered out the approximately 20-person crowd. No arrests were made.

Before the board met again in public last Wednesday, supervisors rehearsed emergency evacuation drills, according to people familiar with the training who spoke on the condition of anonymity as they are not allowed to talk about security measures publicly.

Video cameras were added to the chamber and about a dozen uniformed and undercover law enforcement officers or security guards stood watch during the meeting. Sheriff’s deputies swarmed outside and, away from public view, members of a SWAT team had gathered in case they were needed. The board cordoned off rows of seats closest to the dais and required that speakers during the public comment period be escorted to the microphone.

The most popular portion of the meeting — a pet showcase that helps to match homeless dogs with new owners — took place virtually to reduce activity in the chamber and keep employees safe.

“Please know that this is done to protect your safety as well as ours,” Jack Sellers (R), chairman of the board, told the crowd, speaking of the new security measures.

Outside the meeting, Klann and others asserted without evidence that the county board represented foreign interests — not constituents of Maricopa County. Klann declined to answer questions.

The crowd that confronted county leaders on Feb. 28 included supporters of a new Arizona-based anti-government group that Klann co-founded called The Peoples Operation Restoration. The group’s website features a painting of Trump dressed as a Founding Father and riding a horse.

Citing false claims that the 2020 election was stolen and challenges to the validity of U.S. laws and structures, supporters have shown up to Maricopa meetings and offices in recent weeks delivering paperwork that falsely claims leaders are illegitimate and have broken the law.

Klann and supporters gained attention for a similar effort waged against school boards around the nation involving pandemic-era public health measures, said Katie McCarthy, an investigative researcher for the Anti-Defamation League’s Center on Extremism. The strategy, she said, had served as a “harassing intimidation tactic” that is now being echoed in the election denial movement in Arizona.

Some in the group that gathered outside the chamber on Wednesday said they did not recognize the county supervisors’ authority because they do not believe the results of the 2020 election. They said they came to know each other during the post-2020 review of 1.1 million ballots in metro Phoenix, which affirmed Biden’s win.

“We’d like them replaced,” said Brenda Ireton, a pro-Trump Republican who said she views the board as “corrupt” and “bought and paid for” by unknown interests.

Inside the chamber, the board moved quickly through its agenda. When the pro-Trump activists entered, about 15 minutes after the meeting had begun, at least one of them live-streamed on a phone while another carried professional-looking camera gear. As the meeting entered a period reserved for public comment, the group began to loudly complain that they were not allowed to speak. They had missed the deadline — 10 minutes after the meeting had started — to submit paperwork to do so.

As the meeting barreled to an end and supervisors spoke about community events in their districts, the shouting began. Supervisor Thomas Galvin (R) thanked officers in the room for protecting them.

“You’re an insurrectionist,” a woman jeered.

Galvin shot back: “Your performance is noted.” The board chair stepped in, warning those disrupting the meeting that he would have them removed if they continued shouting.

“Every single two weeks we try to do this here,” Galvin told the attendees. “This is the people’s business — we represent 4.5 million people in this county. You don’t get to control what people get to hear.”

Amid another fraught election season, county leaders are drafting rules for public meetings as a way to try to force civility — and make clear the consequences for those who disrupt the board’s work, according to three people familiar with the discussions. The county must vote on any proposed rules before they take effect, possibly within the next two months.

The rules could become critical to the board’s ability to perform its duties, including the approval of election results. Supervisor Bill Gates (R) declined to speak about the proposed rules, but said that he appreciated the board chairman’s work behind-the-scenes to try to balance First Amendment rights with the board’s attempts to do its work without disruption.

“In a year filled with what’s expected to be difficult meetings,” said Gates, who has been the target of particularly intense attacks, “it’s important to be able to maintain control.”

Usero reported from Washington.