BROOKFIELD, Wis. >> Sen. Ron Johnson incited widespread outrage when he said recently that he would have been more afraid of the rioters who rampaged the Capitol on Jan. 6 had they been members of Black Lives Matter and antifa.

But his revealing and incendiary comment, which quickly prompted accusations of racism, came as no surprise to those who have followed Johnson’s career in Washington or back home in Wisconsin. He has become the Republican Party’s foremost amplifier of conspiracy theories and disinformation now that Donald Trump is banned from social media and largely avoiding appearances on cable television.

Johnson is an all-access purveyor of misinformation on serious issues such as the pandemic and the legitimacy of American democracy, as well as invoking the etymology of Greenland as a way to downplay the effects of climate change.

In recent months, Johnson has sown doubts about President Joe Biden’s victory, argued that the Jan. 6 attack on the Capitol was not an armed insurrection, promoted discredited COVID-19 treatments, said he saw no need to get the coronavirus vaccine himself, and claimed that the United States could have ended the pandemic a year ago with the development of a generic drug if the government had wanted that to happen.

Last year, he spent months as chair of the Senate Homeland Security Committee seeking evidence that Biden had tried to pressure Ukrainian officials to aid his son Hunter Biden, which an Intelligence Community report released today said was misinformation that was spread by Russia to help Trump’s reelection.

Johnson has also become the leading Republican proponent of a revisionist effort to deny the motives and violence of the mob that breached the Capitol. At a Senate hearing to examine the events of that day, Johnson read into the record an account from a far-right website attributing the violence to “agents-provocateurs” and “fake Trump protesters.” On Saturday, he told a conference of conservative political organizers in Wisconsin that “there was no violence on the Senate side, in terms of the chamber.” In fact, Trump supporters stormed the chamber shortly after senators were evacuated.

His continuing assault on the truth, often under the guise of simply “asking questions” about established facts, is helping to diminish confidence in U.S. institutions at a perilous moment, when the health and economic well-being of the nation relies heavily on mass vaccinations, and when faith in democracy is shaken by right-wing falsehoods about voting.

Republicans are 27 percentage points less likely than Democrats to say they plan to get, or have already received, a vaccine, a Pew Research Center study released this month found. In an interview, Johnson repeatedly refused to say that vaccines were safe or to encourage people to get them, resorting instead to insinuations — “there’s still so much we don’t know about all of this” — that undermine efforts to defeat the pandemic.

The drumbeat of distortions, false theories and lies reminds some Wisconsin Republicans of a figure from the state’s past who also rarely let facts get in the way of his agenda: Sen. Joseph McCarthy, whose witch hunt for communists in and out of government in the 1950s ruined lives and bitterly divided the country.

“Wisconsin voters love mavericks, they really love mavericks — you go way back to Joe McCarthy,” said Jim Sensenbrenner, a long-serving Republican congressman from the Milwaukee suburbs who retired in January. “They do love people who rattle the cage an awful lot and bring up topics that maybe people don’t want to talk about.”

For Democrats, who have never forgotten Johnson’s defeat of liberal darling Russ Feingold in 2010 and again in a 2016 rematch, regaining the Senate seat in 2022 is a top priority. Although he has yet to announce whether he would be seeking a third term, Johnson recently said that the fury that Democrats had directed his way had made him want to stay in the fight. Still, he has raised just $590,000 in the past two years — a paltry sum for an incumbent senator.

Johnson’s most recent provocation came March 12, when he contrasted Black Lives Matter protesters to the Trump supporters “who love this country” and stormed the Capitol, the carnage resulting in 140 injured police officers and more than 300 arrests by federal authorities. During an interview with a right-wing radio host, Joe Pagliarulo, Johnson said, “Joe, this will get me in trouble. Had the tables been turned and President Trump won the election and those were tens of thousands of Black Lives Matter and antifa protesters, I might have been a little concerned.”

Research on the protests against racial injustice over the summer showed that they were largely nonviolent.

In an interview with The New York Times, Johnson rejected comparisons to McCarthy. And he insisted he had no racist intent in making his argument.

“I didn’t feel threatened,” he said. “So it’s a true statement. And then people said, ‘Well, why?’ Well, because I’ve been to a lot of Trump rallies. I spend three hours with thousands of Trump supporters. And I think I know them pretty well. I don’t know any Trump supporter who would have done what the rioters did.”

On Sunday, Sen. Roy Blunt, R-Mo., denounced Johnson’s distortion of the events of Jan. 6. “We don’t need to try and explain away or come up with alternative versions,” he said on the NBC program “Meet the Press.” “We all saw what happened.”

Johnson, in the Times interview, also faulted the federal government for what he called its “tunnel vision” pursuit of a COVID-19 vaccine while not more deeply studying treatments such as hydroxychloroquine — the anti-malarial drug promoted by Trump that the Food and Drug Administration says is not effective against the virus. That strategy, he said, cost “tens of thousands of lives.”

Conspiracy theories and a defiant disregard of facts were a fringe but growing element of the Republican Party when Johnson entered politics in 2010 — notably in the vice presidential candidacy of Sarah Palin two years earlier. But under Trump, the fringe became the mainstream. Fact-free assertions by the president, from the size of his inaugural crowd in 2017 to the “big lie” of a stolen election in 2020, required Republican officials to fall in line with his gaslighting or lose the support of the party’s base voters.

Johnson proved himself remarkably adept at adopting the misinformation that increasingly animated Fox News commentators and right-wing talk radio.

“Through the years, as the party has morphed into a muscular ignorance, QAnon sect, he’s followed along with them,” said Christian Schneider, a former Republican political operative in Wisconsin who embedded with the Johnson campaign in 2010 to write a glowing account for a local conservative magazine. “Now he’s a perfect example of that type of politics.”

Johnson was the CEO of a plastics company started by his wife’s family when he first ran for the Senate in 2010. He campaigned as a new-to-politics businessman concerned about federal spending and debt, and he spent $9 million of his own money on the race.

But there were signs in that first campaign of Johnson’s predilection for anti-intellectualism. On several occasions, he declared that climate change was not man-made but instead caused by “sun spots” and said excess carbon dioxide in the atmosphere “helps the trees grow.” He also offered a false history of Greenland to dismiss the effects of global warming.

“You know, there’s a reason Greenland was called Greenland,” Johnson told WKOW-TV in Madison, Wisconsin, back then. “It was actually green at one point in time. And it’s been, you know, since, it’s a whole lot whiter now, so we’ve experienced climate change throughout geologic time.”

In the interview Thursday, Johnson was still misinformed about the etymology of Greenland, which got its name from explorer Erik the Red’s attempt to lure settlers to the ice-covered island.

“I could be wrong there, but that’s always been my assumption that, at some point in time, those early explorers saw green,” Johnson said. “I have no idea.”

Just as Trump would later use Fox News to build a national political persona, Johnson did so on Wisconsin’s wide network of conservative talk-radio shows. His political rise would not have been possible without support from Charlie Sykes, then an influential radio host in Milwaukee who once read an entire 20-minute speech by Johnson on the air.

Sykes, who since 2016 has been a harsh critic of Trump-era Republicans, said last week of Johnson, “I don’t know how he went from being a chamber of commerce guy to somebody who sounds like he reads the Gateway Pundit every day. He’s turned into Joe McCarthy.”

This month alone, Johnson has made at least 15 appearances on 11 different radio shows.

On Tuesday he appeared with Vicki McKenna, whose right-wing show is popular with Wisconsin conservatives. She began by attacking public health guidance on wearing a mask and maintaining social distance, arguing it is a Democratic plot to control Americans. Johnson agreed with McKenna and her assessment that public health experts in the federal government are misleading the country when they promote the coronavirus vaccine.

“We’ve closed our minds to all of these other potentially useful and cheap therapies, all on the holy grail of a vaccine,” he said. Dr. Anthony Fauci, he added, is “not a god.”

In the interview, the senator said it was not his responsibility to use his public prominence to encourage Americans to get vaccinated.

“I don’t have all the information to say, ‘Do this,’” Johnson said.

His false theories about the virus and the vaccine are reminiscent of other misinformation that Johnson has amplified. During a 2014 appearance on Newsmax TV, he warned of Islamic State group militants infecting themselves with the Ebola virus and then traveling to the United States. In 2015, he introduced legislation directing the federal government to protect itself against the threat of an electromagnetic pulse, a conspiracy theory that has long lived on the far-right of U.S. politics.

Last year’s monthslong investigation by Johnson’s Homeland Security Committee into the Bidens and Ukraine concluded with the GOP majority report finding no wrongdoing by the former vice president. An Intelligence Community assessment declassified and released today concluded that Russia had spread misinformation about Hunter Biden to damage his father’s campaign and to help Trump win reelection.

Johnson, who was not named in the assessment, was adamant that his work was not directly or unwittingly influenced by Russians.

“Read the report; show me where there’s any Russian disinformation,” he said. “Anybody who thinks I spread disinformation is uninformed because I haven’t.”

For weeks after the November election, Johnson refused to acknowledge Biden as the winner while echoing Trump’s false statements about rampant fraud. He convened his committee in December to air baseless claims of fraud and mishandling of ballots, even as dozens of claims of fraud made by the Trump campaign were being tossed out of courts across the country.

In a cascade of interviews with friendly conservative outlets, Johnson has lately portrayed himself as a victim of “the radical left” that is waging a scorched-earth campaign to flip his Senate seat.

“The best way to maintain power is to destroy your political opposition, and they’re targeting me,” he told Oshkosh, Wisconsin, radio host Bob Burnell on Tuesday. “This is obviously a vulnerable Senate seat in a swing state, so they think I’d probably be the target No. 1. And I am target No. 1.”

Johnson’s defenders say he is fighting the liberal media’s attempts to silence him.

“I see the same thing happening with Sen. Johnson that the media did with Donald Trump,” said Gerard Randall, chair of the Republican Party of Wisconsin’s African-American Advisory Council. “I know Sen. Johnson personally, and I know that he is not a racist.”

If Johnson seeks a third term, the race is likely to be decided in the Milwaukee suburbs, which used to deliver Republican landslides but have moved away from the party since the Trump era.

The city of Brookfield, for example, backed Trump by a margin of just 9 percentage points in November after voting for him by 20 points in 2016 and President George W. Bush by 39 points in 2004.

“There was a lot of eye-rolling” about Johnson’s recent comments about the Capitol siege, said Scott Berg, a conservative who has served as a Brookfield city alderman for 20 years. “If I were in the leadership of the Wisconsin Republican Party, I’d be out shopping for candidates” for the Senate in 2022, he added.

Still, in 2016, Johnson ran 10 percentage points ahead of Trump in Brookfield. Voters there suggested the suburb might not be drifting from Republicans as fast as some Democrats had hoped.

“I’m a Johnson supporter — I voted for him twice — but I think he’s going down a rabbit hole I don’t want any part of,” said John Raschig, a retiree who was leaving a Pick ‘n Save supermarket. “It’s sort of like Trump: I’d vote for him because the other side’s awful, but I’d prefer somebody else.”