Trump supporters march down Constitution Avenue before a mob breached the U.S. Capitol on Jan. 6, 2021. Michael Robinson Chávez/The Washington Post

A quarter of Americans say it is “probably” or “definitely” true that the FBI instigated the Jan. 6, 2021, attack on the U.S. Capitol, a false concept promoted by right-wing media and repeatedly denied by federal law enforcement, according to a new Washington Post-University of Maryland poll.

The Post-UMD poll finds a smaller 11% of the public overall thinks there is “solid evidence” that FBI operatives organized and encouraged the attack, while 13% say this is their “suspicion only.”

Among Republicans, 34% say the FBI organized and encouraged the insurrection, compared with 30% of independents and 13% of Democrats.

The results confirm that misinformation about Jan. 6 is widespread as the United States heads into a presidential election year, during a campaign in which the former president and leading 2024 Republican candidate Donald Trump has repeatedly expressed support for those who participated in the insurrection.

Despite a detailed congressional investigation and more than 725 completed federal prosecutions of Jan. 6 participants that did not yield evidence of FBI involvement, a substantial minority of Americans still embrace conspiracy theories not unlike the ones that drove many rioters to storm the Capitol three years ago.

“The people that went there to express their views, to support Trump, were peaceful,” said Richard Baum, 61, an independent voter from Odessa, Tex. “The government implants were the violent ones: the FBI, the police people that were put in there, the antifa and BLM hired by George Soros; everybody knows that.”

The Post-UMD poll finds 39% of Americans who say Fox News is their primary news source believe the FBI organized and encouraged the Jan. 6 attack, compared with 16% of CNN or MSNBC viewers and 13% who get most of their news from ABC, CBS or NBC. The poll finds 44% of those who voted for Trump say the FBI instigated the attack.

About 700 Jan. 6 defendants have pleaded guilty to federal crimes ranging from trespassing to violent assaults on police, and another 130 have been convicted at trial, after Trump directed angry supporters to march to the Capitol to oppose Congress’s confirmation of the 2020 election results. In numerous hearings and trials, attorneys for defendants – including “QAnon Shaman” Jacob Chansley and ex-Proud Boy leader Henry “Enrique” Tarrio – have blamed Trump for the attack or their behavior in subsequent rioting that day, citing Trump’s encouragement to “fight like hell” and his false claims of massive voter fraud.

The FBI has categorically rejected allegations of any involvement in sparking the Capitol riot. “This notion that somehow the violence at the Capitol on January 6 was part of some operation orchestrated by FBI sources and agents is ludicrous,” FBI Director Christopher A. Wray said during a House hearing in July, “and is a disservice to our brave, hard-working, dedicated men and women.”

But the vast legal and evidentiary record to date has not appeared to sway people such as Travis Garcia, 34, a Republican from Rock Falls, Ill., who said, “I’ve read and seen a lot about these people being affiliated with the FBI.” He cited a man who fits the description of Ray Epps, saying he was “trying to egg on violence before anything even happened.” Epps, who became a focus of a conspiracy theory that the federal government ignited the Capitol riot, has pleaded guilty to trespassing and filed suit against Fox News for falsely depicting him as an FBI operative.

The poll results sparked dismay, but not surprise, among experts in disinformation and American media consumption.

“The finding that 25% believe the FBI was responsible for the Jan. 6 attack, sadly, fits in with the general nonsense and lies that are swirling around social and mainstream media,” said Hany Farid, a professor at the School of Information at the University of California at Berkeley.

For example, a 2023 KFF poll last year found 34% believed the false claim that coronavirus vaccines have caused sudden deaths for thousands of healthy people, and a 2021 PRRI poll found 15% agreeing with a QAnon conspiracy theory that Satan-worshiping pedophiles control government, media and financial worlds.

“Whereas 20 years ago we may have argued about how or if to respond to events” such as the Capitol riot, Farid said, “today we are arguing about basic facts that are objectively and easily verifiable. … We should all be greatly concerned for our democracy and societal stability.”

Alex R. Piquero, a professor of sociology and criminology at the University of Miami and former head of the federal Bureau of Justice Statistics, said people self-select their news and, in doing so, self-select the facts that reinforce what they believe.

Piquero said in an interview that the legitimacy of the 2020 election, skepticism of which motivated the attack on the Capitol, had been upheld in more than 60 court cases and confirmed by countless authorities on both sides of the political aisle.

“Sometimes, for some people, no amount of data is going to change their mind,” Piquero said. “If you were to ask some people, do you trust the airplane you fly in? When you go get medicine from your doctor? It comes from science and data. People are willing to be okay on some of those things that are helpful to them, but when it contradicts their worldview, that’s when it gets fuzzy and unfortunate.”

Debunked rhetoric about the Jan. 6 attack has not been limited to the FBI conspiracy. Some have alleged that anti-Trump antifa instigated the riot or that police were complicit in the building breach, fueling calls for the release of Capitol surveillance footage from that day that in turn re-energized claims of FBI involvement.

Partisan divisions over Jan. 6 are clear in the poll. Almost 8 in 10 Democrats (77%) say that those who entered the Capitol were “mostly violent,” compared with 18% of Republicans, down slightly from 26% in 2021. About 140 police officers were assaulted on Jan. 6 at the Capitol, federal authorities have said, and more than 90 people have already been sentenced for felony assaults on law enforcement caught on video, with many similar cases still pending, according to a Post database.

Partisans are also split over the punishments for those charged in the Capitol riot. The Post-UMD poll finds 42% of Republicans say the punishments have been “too harsh,” up from 32% two years ago, while 60% of Democrats say the punishments were “not harsh enough.”

Post data shows the average sentence for a Jan. 6-related felony conviction is about 41 months, with judges imposing jail or prison in 94% of felony cases. For defendants charged only with misdemeanors, who make up about two-thirds of the Jan. 6 cases, about half have received jail terms averaging 58 days while the other half have received probation or home detention, the Post database shows.

Overall, 50% of Americans say the rioters were “mostly violent,” down slightly from 54% in a 2021 poll. “It was very, very violent,” said Kathleen Lenk, 62, a Democrat from Minneapolis. “I watched the video with my own eyes, of people beating policemen, injuring people.” Lenk felt the FBI was not involved in the riot but should have taken more steps to stop it based on advance warnings received by law enforcement.

Edmund Pirali, 57, a Democrat from Sykesville, Md., was discouraged by the finding that a quarter of Americans think the FBI was involved in Jan. 6. “I am so disheartened,” Pirali said, “about the dissociation in America from reality and fact. And it’s so pervasive.” He likened the belief in FBI involvement to believing in alien body snatchers and a flat Earth. “Of course not,” Pirali said.

Some of those who believe in the FBI’s involvement are very firm in their opinions. “I think it was all for Joe Biden,” said January Vasquez, 48, of Berlin, Conn. “Because it’s a conspiracy. Everything happens for a reason.” She acknowledged some Trump supporters may have “crossed the line” at the Capitol, “but sometimes in life you gotta shake it up. Everybody’s got a price tag. Somebody got paid to set that … up.” Vasquez said her news sources were local television stations, CBS and CNN.

Baum, of Odessa, said with the release of surveillance videos inside the Capitol on Jan. 6 to conservative news outlets, “you can clearly see there was nobody killed. Everybody that walked through the halls, peaceful. You even had Capitol Police escorting them through it. The people that said it was an insurrection, that was a joke.”

QAnon follower Ashli Babbitt was killed by police, and three other rioters died in the violence at the Capitol on Jan. 6. Multiple police officers died by suicide in the subsequent months. Surveillance video shown by media personalities such as Tucker Carlson omitted footage of violent clashes between police and Trump supporters both inside and outside the Capitol.

Asked why so many people have pleaded guilty to rioting charges if the FBI is to blame, Baum said that “the system targets you.”

“It’s political piracy,” he said, adding: “You still have people being detained but not being charged. You better look into it. A lot of people that are being detained, they’re just being held.” He said video showed those who fought with police were “FBI plants” and “agitators that were being paid by Soros or his group.” Baum said his sources of information were One America News, podcaster Dan Bongino, and Glenn Beck and his website the Blaze.

The U.S. attorney’s office in Washington recently released a list of 18 people still detained before trial on Jan. 6 charges and said no one has been held without charges.

The Post and the University of Maryland’s Center for Democracy and Civic Engagement conducted this poll Dec. 14-18 among a random national sample of 1,024 U.S. adults through NORC at the University of Chicago’s AmeriSpeak Panel. It has an error margin of plus or minus 4.1 percentage points for the full sample.