Law enforcement officials in California and across the country are preparing for threats against election workers, violence at polling places and voter intimidation amid skepticism from Republicans about the integrity of the voting process.

Polling places and locations where ballots are counted have beefed up security in advance of Tuesday’s election, deploying bomb- and firearm-sniffing dogs, metal detectors, panic buttons and even rooftop snipers to protect workers and voters.

The U.S. Attorney’s Office for the Central District of California has for months been working with voting officials, police and sheriff’s departments to prevent threats to election workers, respond to election-related security issues and violations of voting law in Los Angeles, Orange, Riverside, San Bernardino, Ventura, Santa Barbara and San Luis Obispo counties, U.S. Atty. Martin Estrada said.

“My office will be vigilant in upholding the ability of each citizen to vote freely and fairly — without interference or discrimination,” Estrada said in a statement. “Likewise, election officials and staff must be able to work in safety. We will continue our tireless efforts to safeguard our nation’s elections.”

Since the 2020 election, voting centers have been forced to ramp up safety measures in response to the harassment of election workers. Much of the problems stemmed from former President Trump’s rejection of his loss to President Biden and his false claims that the election was stolen from him.

Unfounded allegations of election tampering prompted large turnouts at “Stop the Steal” protests across the country, which eventually culminated in Trump supporters storming the U.S. Capitol on Jan. 6, 2021, to try to block Congress from confirming the election results.

More than third of election officials surveyed this year by the Brennan Center for Justice at New York University School of Law said they have been harassed, threatened or abused for carrying out their work. Those threats have increased in the years since 2020, the poll showed.

Experts say threats could continue even after ballots are counted, with tensions remaining high all the way until Inauguration Day.

“Perhaps most daunting during this change of power period is the breadth of those distrusting government, whose aggression and conspiracism is further fanned and directed by mainstream politicians and online manipulators,” said Brian Levin, the founder of the Center for the Study of Hate and Extremism. “Part of this present elevated risk is tied to the rhetoric of former President Trump and the length and trajectory of his verbal targeting in it.”

Federal law prohibits threatening election officials or staff with violence, intimidating or bribing voters, buying or selling votes, impersonating voters, altering vote tallies, stuffing ballot boxes and marking ballots for voters without their input. The Federal Bureau of Investigations will have agents in each field office across the country poised to probe allegations of election fraud or other abuses on election day, Estrada said.

Art Acevado, a former police chief in Miami, Houston and Austin, said law enforcement agencies have put an unprecedented amount of time and energy into preparing for Tuesday as doubts about the vote and concerns about violence continue to climb. The efforts, he said, “demonstrate the heightened threat environment our nation is facing.”

“Agencies are taking steps to protect ballot boxes, polling stations, election offices, and all components essential to ensuring free and fair elections. Law enforcement is the most visible part of the institutional system that keeps Americans safe and is the most impacted by the chaos and division that may arise in our country,” Acevado said. “The men and women in blue may find themselves caught in the crossfire caused by the potential violence sparked by misinformation campaigns from foreign hostile nations and some American political operatives.”

Los Angeles County Sheriff Robert Luna said there have not been any credible threats to polling locations or toward poll workers in the county, but the department is continuing to monitor the situation. Election security was a hot topic among police chiefs at a policing conference in Boston last month, he said.

“We have to be concerned,” Luna said. “Look at the rhetoric, the back and forth. We always tell people it’s okay to disagree, but you can’t go [to] fisticuffs, and you can’t act on your desires for violence.”

In Orange County, Registrar of Voters Bob Page has posted the various steps of ballot collection and counting on social media in an effort to quell concerns by shedding light on the process. The county, which has transitioned in recent decades from a solidly Republican swath to a more political diverse region, has its share of election skeptics. In a UC Irvine poll this year, 26% of adults surveyed said they did not believe Biden legitimately won the presidency in 2020, with another 17% unsure whether he did.

“We work very closely with law enforcement at the federal, state and local levels as well as with our prosecutors … to keep our voters safe, our staff safe but also to investigate potential fraud,” Page said in an Instagram video last week.

Security concerns and even attempts at election interference emerged weeks ago.

The Office of the Director of National Intelligence, Federal Bureau of Investigation, and Cybersecurity and Infrastructure Security Agency determined last week that a recent video circulating online that depicted individuals claiming to be from Haiti and voting illegally in multiple counties in Georgia were manufactured by Russian influence actors.

The group also created a video falsely accusing someone associated with Vice President Kamala Harris’ presidential campaign of taking a bribe. The goal of the videos, officials said, was to “raise unfounded questions about the integrity of the U.S. election and stoke divisions among Americans.”

Ballot boxes in Portland, Ore., and Vancouver, Wash., were burned last week, damaging hundreds of ballots — a move that local authorities said was “targeted and intentional.”

Washington Gov. Jay Inslee said Friday he was calling up the Washington National Guard to protect election infrastructure and respond to any unrest related to the election. Some election officials across the country have installed panic buttons at election offices to alert law enforcement and even bullet-resistant glass to protect poll workers.

Nevada Gov. Joe Lombardo announced a “precautionary activation” of the Nevada National Guard for the election. Nearby, in Arizona — also a battleground state for the presidential election — Democratic Secretary of State Adrian Fontes revealed in a recent court hearing that he wears a bulletproof vest during election season.

At the Maricopa County Ballot Tabulating Center in Arizona, two layers of security fencing surround the building. There’s metal detectors and even rooftop snipers.

Glen Kucera, president of Allied Universal Enhanced Protection Services, said the company is deploying security teams across the country to assist with threats on election day.

Some of the security company’s customers will host polling sites on Tuesday, so Allied employees are doing surveillance at those locations looking for “bad actors, anything out of the ordinary, and reporting back to law enforcement and those customers on any potential threats that we may see,” Kucera said.

They will also deploy canines that have the ability to find explosives and firearms, he said.

“It’s a lot more this year than ever, and I think it’s just because there’s so much turmoil,” Kucera said of the security concerns leading up to Tuesday. “The Middle East is in conflict. There’s the Ukraine and Russia conflict, North Koreans are involved, and probably now more so than ever that threat resides inside the borders of the United States.”

Times staff writer Faith Pinho contributed to this report.