More than half of Republicans blame the Jan. 6 Capitol attack on“left-wing” rioters, a new poll finds. 

About half of Republicans still do not accept the verified fact that conservative protesters, supporters of former President Donald J. Trump, attacked the U.S. Capitol on Jan. 6, according to a poll released Monday.

Overall, 61 percent of Americans think Mr. Trump “is at least partly to blame for starting the deadly Jan. 6 riot” — but only 28 percent of Republicans agreed with that statement, according to a new Reuters/Ipsos poll.

And 55 percent of Republicans believe that the riot was started by “violent left-wing protesters trying to make Trump look bad.” The F.B.I. has said there is no evidence to support those claims.

Moreover, six in 10 Republicans also believe Mr. Trump’s false assertion that the presidential election “was stolen” from him as result of widespread ballot fraud — while around 80 percent in the party want him to run again in 2024.

But only three of 10 independents, swing voters who sway the results of many tight races, had a favorable view of Trump, while 60 percent do not want Mr. Trump to run again. (The poll had a margin of error of about 4 percentage points.)

The survey, which was conducted online last week with responses from 1,005 adults around the country, is a vivid illustration of the effectiveness of misinformation efforts, echoed by right-wing social media.

Investigators, news outlets and congressional committees have demonstrated — with comprehensive and unmistakable visual, audio and documentary evidence — that the rioters who stormed the Capitol were supporters of Mr. Trump. They were chanting pro-Trump slogans, tried to find legislators they deemed hostile to the former president and were, in part, organized by far-right groups, including the Proud Boys.

Mr. Trump has downplayed his role in inciting the attack and recently told Fox News that the rioters posed “zero threat,” despite law enforcement agencies reporting injuries to at least 138 officers — 73 from the Capitol Police and 65 from the Metropolitan Police Department in Washington. One Capitol Police officer, Brian D. Sicknick, was killed.

Republicans, including Senator Mitch McConnell, the minority leader, have complained about the cordon of security around the complex, arguing that it is unnecessarily restrictive, while others have boasted about bypassing magnetometers installed outside the House chamber.

Dangers persist, however. On Friday, a man rammed into a security checkpoint near the Capitol, killing one officer and seriously injuring another. The man was shot and killed after jumping out of his car and lunging toward the officers with a knife.