In a sharply worded online post condemning Senate Democrats for engaging in "baseless innuendo and more false smears," Judiciary Committee Republicans on Wednesday stood by their claim that none of Supreme Court nominee Brett Kavanaugh's previous FBI background checks had turned up any evidence of sexual misconduct.

The brouhaha began when GOP committee staffers wrote Tuesday on Twitter: "Nowhere in any of these six FBI reports, which the committee has reviewed on a bipartisan basis, was there ever a whiff of ANY issue – at all – related in any way to inappropriate sexual behavior or alcohol abuse."

Kavanaugh underwent those prior FBI screenings, starting in 1993, because of his work in various high-level federal government positions, including his stint with the White House Counsel and his current post as an appellate judge. The agency interviewed more than 150 people as part of those probes.

On Wednesday, eight Senate Democrats on the Judiciary Committee wrote, "While we are limited in what we can say about this background investigation in a public setting, we are compelled to state for the record that there is information in the [Twitter] post that is not accurate."

They continued: "It is troubling that the Committee Majority has characterized information from Judge Kavanaugh's confidential background investigation on Twitter, as that information is confidential and not subject to public release." Democrats also pointed to what they said was Republicans' improper disclosure about two witnesses who had come forward to claim that they, not Kavanaugh, had assaulted California professor Christine Blasey Ford.

But a source familiar with the confirmation process told Fox News that, if the materials the Democrats were referring to actually became public, “they would be laughed out of the room.” The source called the Democrats' letter a "joke."

And in another tweet on Wednesday, Senate Republicans held their ground.

"Nothing in the tweet is inaccurate or misleading," they wrote. "The committee stands by its statement, which is completely truthful. More baseless innuendo and more false smears from Senate Democrats."

Notably missing from the Democrats' letter were Minnesota Sen. Amy Klobuchar and Delaware Sen. Chris Coons. It was not immediately clear whether they disagreed with the content of the letter, which also called for a "full Senate briefing with the FBI" when it releases its much-anticipated supplemental background check on Kavanaugh this week.

Coons brokered the last-minute deal on Friday with Sen. Jeff Flake, R-Ariz., to conduct that supplemental probe before a full floor vote on Kavanaugh's confirmation. Since then, Coons and Flake have appeared several times together publicly and on national television, touting the importance of a fair-minded, bipartisan confirmation process.

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The Delaware Democrat also didn't sign another letter over the weekend that Senate Judiciary Democrats sent to White House Counsel Don McGahn and FBI Director Christopher Wray listing two dozen witnesses they wanted the FBI to interview during its background probe.

At the time, Coons told Fox News: "I was very busy on Sunday and Monday talking with colleagues conveying my concerns about the scope of the investigation and frankly didn't sign off on that letter. That wasn't meant as any sign of disrespect to my Democratic colleagues. ... I just felt I was pursuing other ways to express my concerns."

Even as Democrats cite the previous confidential FBI background checks on Kavanaugh, they are fiercely criticizing the FBI's ongoing supplemental review as a potential "farce." Lawyers for Ford, who alleged that Kavanaugh sexually assaulted her more than three decades ago, complained in a letter to Wray this week that they had gotten "no response" when they requested that agents interview their client.

On Wednesday, Ford's lawyers told Senate Republicans they would turn over documents they had requested -- including, potentially, her therapist notes and polygraph reports -- only if the FBI contacted them immediately.

Apparently responding to those complaints, Senate Judiciary Committee Chairman Chuck Grassley, R-Iowa, accused Democrats this week of improperly meddling in the investigative process.

“The FBI conducts background investigations in accordance with the agency’s standard operating procedures, and it has done so six previous times for Judge Kavanaugh," Grassley wrote. "I’m confident that the FBI agents tasked with this responsibility will not succumb to public political pressure or politicians telling the agency how to do its job. Respectfully, the career public servants and professionals at the FBI know what they’re doing and how best to conduct a background investigation."

Fox News' John Roberts, Jason Donner and Mike Emanuel contributed to this report.