Normally during a presidential debate, it is the candidates who defend their records against attacks from their rivals. On Saturday night, it was CNN.
CNN took the extraordinary step of sending out a press release during an ABC News Debate accusing Sen. Ted Cruz of "knowingly" misrepresenting its reporting about the Ben Carson campaign.
"The Cruz campaign's actions the night of the Iowa caucuses had nothing to do with CNN's reporting. The fact that Senator Cruz continues to knowingly mislead the voters about this is astonishing," CNN said.
The flap is unlikely to hurt Cruz, who has often reveled in sparring with the media and the debate moderators.
What began the fight between Ted Cruz, CNN
Before the Iowa caucuses, Ted Cruz's campaign said rival Ben Carson would be "suspending campaigning" after the vote -- an apparent attempt to persuade Carson caucus-goers to swing to Cruz at the last minute. But the the claim was not true.
The Cruz campaign left voicemails with caucus-goers that said Carson would be "taking a leave of absence from the campaign trail, so it is very important that you tell any Ben Carson voters that for tonight, uh, that they not waste a vote on Ben Carson."
Cruz tried ducking responsibility for these false messages during Saturday night's Republican primary debate by blaming CNN's reporting.
"CNN reported that Ben was not going from Iowa to New Hampshire or South Carolina, rather, he was, quote, 'taking a break from campaigning,'" Cruz said. "My political team saw CNN's report breaking news and they forwarded that news to our volunteers."
Cruz also accused CNN of failing to promptly correct its reporting about the Carson campaign.
CNN issues statement saying Cruz is getting the facts wrong in an "astonishing" way
There's a simple problem with Cruz's statement: CNN never reported that Carson was going to be suspending his campaign.
"What Senator Cruz said tonight in the debate is categorically false. CNN never corrected its reporting because CNN never had anything to correct," CNN said in a story posted to its website during the debate.
CNN had reported that Carson would be going to Florida after Iowa rather than New Hampshire. But CNN "never reported nor implied that Carson was going to suspend his campaign, as Cruz's campaign did," CNN reporter Dylan Byers wrote.
In strong terms that went beyond the network's usually measured tone, CNN condemned Cruz for "knowingly" distorting the facts at the debate.
This is an unusual move for CNN
One of the most frequent criticisms of CNN is that it is more interested in promoting a false equivalency — showing that both sides have a fair point — rather than finding the truth.
The statement about Cruz breaks that mold. Explicitly stating that the Texas senator is stating falsehoods marks a "break-the-glass" escalation of its reporting — a sort of nuclear option for a network committed to maintaining its reputation for evenhanded journalism.
But as many observers pointed out Saturday night, it's unlikely to work.
Cruz has long made attacking the media a key debate strategy, as have many of the Republican presidential candidates. If Donald Trump can openly feud with Fox News host Megyn Kelly, getting called a liar by CNN is unlikely to hurt Cruz with primary voters.