Federal prosecutors are reportedly investigating the false Trump electors' plan to overturn the election.

The January 6 committee documented that the Trump campaign was deeply involved with this effort — part of what Rep. Adam Kinzinger (R-IL) said Sunday amounted to a "seditious conspiracy."

While Johnson initially backed the scheme to reject Biden's win in some of the swing states, he ultimately voted to uphold Biden's win after Trump supporters' invasion of the U.S. Capitol delayed the joint session for several hours.

In September 2021, Wisconsin Public Radio reported that a recording — apparently made without Johnson's awareness — captured the Republican senator admitting that there was "nothing obviously skewed about the results" of the 2020 election in Wisconsin.

"The only reason Trump lost Wisconsin is 51,000 Republican voters didn't vote for him," Johnson said in the recording. "If all the Republicans voted for Trump the way they voted for [Wisconsin State] Assembly candidates, he would have won. He didn't get 51,000 votes other Republicans got — that's why he lost."

In response to a request by the American Independent Foundation for comment, Johnson spokesperson Alexa Henning shared a pair of tweets minimizing — but not actually denying anything about — the committee's findings.

"The senator had no involvement in the creation of an alternate slate of electors and had no foreknowledge that it was going to be delivered to our office. This was a staff to staff exchange. His new Chief of Staff contacted the Vice President's office," Henning wrote. "The Vice President's office said not to give it to him and we did not. There was no further action taken. End of story."

Johnson, who is seeking a third term this November despite promising to limit his tenure to two terms, already faced an uphill battle for re-election before this latest revelation.

The four Democratic candidates seeking the Senate nomination seized on Tuesday's news and condemned Johnson's role in the conspiracy.

Lt. Gov. Mandela Barnes released a statement calling for Johnson to step down: "Ron Johnson actively tried to undermine this democracy. He literally tried to hand Mike Pence fake ballots. Once again, Ron Johnson has proven he's a danger to our country and our fundamental rights. I'm calling for him to resign immediately."

State Treasurer Sarah Godlewski tweeted, "There it is. Ron Johnson was directly involved in the attempt to overturn the 2020 election and overrule the will of Wisconsin voters. He is a threat to our democracy and a disgrace to our state."

Milwaukee Bucks executive Alex Lasry wrote, "Ron Johnson is a seditious traitor and a danger to democracy."

Outagamie County Executive Tom Nelson added: "The @January6thCmte just introduced evidence that fully implicates @SenRonJohnson in the 'fake elector' scheme to overthrow American democracy. Tell me how this isn't a crime? I've called for him to be subpoenaed by the committee. I hope the @USDOJ pays attention as well."