The day after the presidential debate, the phones began to ring at the clerk’s office in Ada County, Idaho, with a handful of residents worried about their safety at the polls. Election officials hastily added training for poll workers on what to do if someone shows up armed.
In Orange County, Calif., law enforcement officers have been given pocket cards detailing the criminal codes on voting disruption, and election personnel have been trained to monitor police radio dispatches for reports of problems at the polls.
In a dozen battleground states, the N.A.A.C.P. has thousands of volunteers preparing to monitor voting lines, all to encourage anyone facing harassment to stay in line and to aggressively use social media to amplify their reports. Another group is taking the unusual step of training volunteers to physically block intimidators.
As early voting accelerates across the nation, election experts say President Trump’s recent statements, emboldened extremist groups and the coronavirus pandemic have combined to create a tension around casting ballots not seen since the Jim Crow era, when civil rights activists were forced to pry open polling places in the South.
“I would have my head in the sand if I didn’t tell you there is not more amplified noise this year,” said Neal Kelley, the Orange County election registrar. “This is the most intense I have seen in 17 years in this job.”
Mr. Trump has sought to enlist both the full force of the federal government and some state government allies into his efforts to sow discord around the election, falsely insisting that mail-in voting is rife with fraud, cheering on the construction of new barriers to voting and encouraging supporters to monitor polls, possibly with the threat of violence.
The president’s confirmed case of coronavirus infection, and his potential absence from the campaign trail, injects even more uncertainty into the final days before the vote.
Mr. Trump’s own government has predicted potential unrest as Election Day approaches.
“Open-air, publicly accessible parts of physical election infrastructure, such as campaign-associated mass gatherings, polling places and voter registration events, would be the most likely flash points for potential violence,” said a September draft of a Homeland Security Department threat assessment. The assessment is set to be issued this month.
Protecting voters from harassment at the polls can be complicated by local and federal laws as well as issues of free speech: One person’s voluble enthusiasm is another’s intimidation. Each state also has its own rules about how close to polling stations protesters and campaign volunteers may stand, but those buffer zones are proving to be less protective than in the past as social distancing has lengthened voting lines.
And other methods to defending polling sites from disruption could be trickier to carry out, especially during a pandemic.
Election officials cannot crowd voters indoors, even to get them away from protesters when that could expose them to coronavirus infection. They could fortify polling sites with law enforcement officials, but that carries its own risk: In some locations, especially those frequented by minority voters, police officers may also be viewed as intimidating.
Those challenges came into focus last month when a group of Trump supporters chanting “four more years” disrupted voters at a polling location in Fairfax, Va., forcing officials at the site to allow the group of voters to wait inside.
But that presented its own problems. Gary Scott, the general registrar of Fairfax County, said the pandemic had further complicated their planning for what he described as the “most contentious” election he had worked in more than 20 years.
After the incident in the Virginia suburbs of Washington, Mr. Scott said he was extending the perimeter outside polling places from which any kind of political advocacy was prohibited from 40 feet to 150 feet. But that has not quelled concerns that voters could be in proximity to potential aggressors, particularly as they are directed to social distance while in line to vote.
“People are out actively stirring the pot,” Mr. Scott said. “There’s a lot of disinformation being disseminated all across the spectrum and that creates a level of anxiety on voters.”
Mr. Scott said his team was meeting with police before the election to consider new security protocols. Officials had private security on hand at the polling place where Trump supporters caused a disruption even before that episode. Such efforts are proliferating around the country as officials are taking the threat seriously.
The F.B.I. and the Department of Homeland Security have begun exercises with local law enforcement groups and election officials around the nation. After participating in one tabletop exercise, David Maeda, a top election official for the Minnesota secretary of state’s office, called his county administrators to ensure they were in contact with their sheriffs and were marking the 100-foot buffer around polling stations. Mr. Maeda is even recommending poll workers attend a roll call at the local police station to make clear the needs of their polling stations.
Steve T. Descano, the county attorney in Fairfax County, has created a team in his office that will soon be trained on the tactics of militia groups. He said the chances of another incident like the one at the polling station in Fairfax were more likely after Mr. Trump called for his supporters to independently monitor polling places during his debate with Joseph R. Biden Jr.
“I told my wife we’re going to have more problems,” Mr. Descano said. “I’m a realist. I always hoped we wouldn’t have problems but I have to plan on it.”
In Weber County, Utah, election officials are running exercises to prepare for “worst-case scenarios” of protesters blocking access to polling places. “Once in a while, you get someone who’s just hot and heavy,” said Ricky Hatch, the county clerk and auditor there.
A slew of groups like the N.A.A.C.P. are also planning to help protect voters by gearing up lawyers and recruiting volunteers to watch for provocations and, if needed, escort voters into their polling place, much like some women get help to enter abortion clinics past protest lines.
“We are training folks to be prepared to deal with provocateurs,” said Ría Thompson-Washington, with the Center for Popular Democracy, even if that means, despite the pandemic, “putting their body between them.” She added, “Usually you would advise them to not engage and divert attention.”
The Lawyers’ Committee for Civil Rights Under Law, a voting rights group, has increased its volunteers from 500 to over 1,200. “We are in high alert in Virginia and George and Kentucky,” said Kristen Clarke, the group’s executive director. “We know this is an unprecedented election.”
Groups that sponsor voter protection programs warn that having a uniformed police presence at polling sites may actually deter voters.
“This is a case where the last thing we want is for law enforcement to show up,” said Kat Calvin, founder of Spread The Vote. “I don’t know if we necessarily are in a country in a climate where we can trust that people would feel like they’re being protected.”
In a recent conference call organized by the National Association of Counties, Michael Vu, the registrar of voters in San Diego County, Calif., said that local officials needed to “strike a balance between free expression and public safety during the pandemic.”
As Election Day draws closer, officials in many counties say they are ready to manage that balance. “I am relatively optimistic,” said Phil McGrane, the county clerk in Ada County. “I’d like to think our community is less likely to experience violence but it is certainly one more thing we are adding to the list.”
Kenneth P. Vogel contributed reporting