Cable news wars can be fierce — and that's fine — but MSNBC just violated the rules of engagement.

A news release distributed by the cable channel on Tuesday began like this:

Today, Alex Conant, Marco Rubio’s communications director, joined MSNBC’s Steve Kornacki to set the record straight on false reports that Rubio is dropping out of the race before the Florida primary. Conant stated: “We are confident we will win there, and when we do, it's going to be a new day on the campaign trail,” adding “I think CNN has a lot of egg on its face.”

On CNN’s report that Marco Rubio is dropping out of the race: “I don't know how a report made it on air without anybody actually checking with the campaign to see if there was any truth to it whatsoever. If they had, they would have known that the report was utter — utterly false. I think that CNN — the story is still on their website. I think that's a problem for them. I don't believe that they are continuing to report on it on air, but they certainly shouldn't have it on the website any longer because it's 100 percent false.”

The problem is CNN quite simply never reported that Rubio "is dropping out of the race," as MSNBC claimed. CNN reported on Monday that some members of Rubio's campaign staff believe he should drop out to avoid a potential defeat next week in Florida, his home state. CNN has said it stands by the report, despite Conant's assertion — live on CNN Monday night — that no one on Rubio's team holds such a view.

There's a huge difference between a story about a campaign's internal discord and a report that a candidate is actually suspending his White House bid. Kornacki, to his credit, made the appropriate distinction on the air, but MSNBC's news release totally mischaracterized CNN's report.

And that's to say nothing of MSNBC saying, in its own words, that the CNN report was "false." As we noted, it's quite possible that people in Rubio's campaign told CNN anonymously how they felt and the campaign higher-ups have no knowledge of it. It's just so hard to prove a negative. That doesn't mean CNN's report is ironclad, just that a rival calling it "false" isn't fair or substantiated.

It's easy enough to understand why a cable news network would get a kick out of a presidential campaign's attack on an industry rival, but there has to be some fraternal respect, too — not to mention a devotion to the actual facts.

To say that a competitor falsely reported something it never reported is fighting dirty. This election has enough of that from the candidates.