A prominent MSNBC contributor’s false claim that Fox News would not air ex-Special Counsel Robert Mueller’s upcoming congressional testimony has morphed into a full-blown conspiracy theory -- and anti-Trump liberals don’t seem to care.

Fox News will cover the highly anticipated hearing in its entirety and has heavily promoted the event, but that didn’t stop everyone -- from an MSNBC anchor to a famed novelist -- from misinforming their fans.

MSNBC CONTRIBUTOR JOYCE VANCE MAKES FALSE CLAIM ABOUT MUELLER TESTIMONY NOT AIRING ON FOX NEWS, DELETES TWEET AFTER CRITICISM

“Fox isn’t showing Mueller’s testimony Wednesday. Trump is afraid of what will happen if his base gets to hear Mueller’s testimony for themselves,” MSNBC contributor Joyce Vance -- who also contributes to the Washington Post -- told her 337,000 Twitter followers on Sunday.

The Obama-appointed U.S. Attorney-turned-MSNBC legal contributor spent much of the afternoon defending her misinformation as "sarcasm" and "irony" before quietly deleting the message hours after it went viral. She even downplayed the notion that her widely inaccurate information would be taken seriously.

Vance was wrong.

“The original tweet from Vance includes nothing that would indicate sarcasm and has no sourcing. This was clearly irresponsible and inappropriate for a contributor to a news organization,” DePauw University professor and media critic Jeffrey McCall told Fox News.

“The original tweet from Vance includes nothing that would indicate sarcasm and has no sourcing. This was clearly irresponsible and inappropriate for a contributor to a news organization." — Jeffrey McCall

On Monday, author Stephen King continued the deception by parroting the false claim to his 5.3 million Twitter followers.

“FOX news shows the president’s rallies but won’t show Robert Mueller’s testimony? What happened to “Fair and Balanced?” King tweeted.

King’s tweet was retweeted more than 6,700 times and liked by over 36,000 people. He has been told numerous times that his tweet is inaccurate but has done nothing to correct the record.

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Liberal Los Angeles Times columnist David Lazarus also tweeted the faulty info: “The fact that Fox News won't cover the Mueller hearings tells you everything you need to know.”

The inaccurate news that Vance chalked up as “sarcasm” and irony” reached millions of people on Twitter by the time MSNBC guest Rick Wilson advanced the falsehood by repeating it on air.

Wilson appeared Monday on MSNBC’s “Deadline: White House” and falsely declared Fox News wouldn’t air the hearing.

“Now Fox isn’t covering the hearings,” Wilson said during a discussion about the upcoming Mueller testimony. “They’re apparently not going to take them live. Everybody else is taking them live.”

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MSNBC’s Nicole Wallace, who is co-anchoring the liberal network’s coverage of the hearing and is presumably well aware of her competition, responded simply by asking, “Really?”

Wallace did not correct Wilson, who later admitted his gaffe on Twitter to a significantly smaller audience. Lazarus eventually realized he spread false information, too, and deleted his original tweet.

MSNBC did not immediately respond when asked if the network would correct this series of misinformation on air. The network did not respond on Sunday when asked if it condoned Vance’s original tweet, either.

On Tuesday, the false information was repeated on MSNBC again, this time by ex-Democratic Congresswoman Donna Edwards. Anchor Stephanie Ruhle, unlike Wallace, chimed in.

“I don’t believe that’s true, I think they are going to air it,” Ruhle said.

“That this false claim has circulated extensively shows how the digital sphere can churn out nonsense so quickly, particularly among people predisposed to believe what they want to believe without additional confirmation." — Jeffrey McCall

“That this false claim has circulated extensively shows how the digital sphere can churn out nonsense so quickly, particularly among people predisposed to believe what they want to believe without additional confirmation,” McCall said. “This also shows the power of traditional media to infuse the news agenda. One news channel contributor tweets a falsehood and it shows up elsewhere on the channel's content, furthering the misinformation.”

Vance appeared on MSNBC for 18 minutes since her misleading tweet ballooned into a viral conspiracy, according to the Media Research Center. Vance was not asked about starting the inaccurate rumor during the air time.

“She never faced even a brief ribbing by a fellow guest or host about her falsehood,” NewsBusters Managing Editor Curtis Houck noted.

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It appears that far-left conspiracy theorists believe that President Trump doesn’t want people to tune in to Mueller’s testimony because damaging information would be revealed. Mueller’s 22-month investigation did not find any evidence of collusion between President Trump’s 2016 campaign and Russia – much to the chagrin of the president’s critics.

Fox News will not only air the testimony, anchored by Bret Baier and Martha MacCallum, but its primetime lineup will provide a thorough analysis of the event, as well. FNC’s coverage, which begins at 8 a.m. ET on July 24, has been heavily promoted.

Meanwhile, CNN’s Brian Stelter fancies himself as a media watchdog who relentlessly defends the fourth estate. Critics have long labeled him a “hall monitor” and media “fire fighter” because his “Reliable Sources” newsletter aims to put a spotlight on various media-related issues.

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Vance’s inaccurate tweet was covered by the Associated Press but ignored by CNN’s “Reliable Sources” newsletter. Wilson’s on-air misinformation and King’s viral tweet were ignored by Stelter, too.

CNN did not immediately respond when asked why the story wasn’t covered.

“It is little wonder news consumers are skeptical of the news industry,” McCall said.

Chris Wallace, Juan Williams, Katie Pavlich, Andrew McCarthy and Ken Starr are part of Fox News' coverage of the Mueller report, in addition to anchors Baier and MacCallum. The network will also air a special edition of “Outnumbered” featuring Harris Faulkner, Sandra Smith, Dagen McDowell and Emily Compagno.