At Donald Trump's first press conference as president-elect, Trump berated and blackballed CNN reporter Jim Acosta for daring to ask questions about his network's bombshell reporting on Trump's relationship with Russia. Even worse, the incoming White House press secretary threatened to throw Acosta out for daring to do his job and ask questions, and another Trump adviser attacked him.

You would expect that the press would be outraged at such behavior from the administration. You would be wrong. The press pretended like none of this ever happened. They ignored that their colleague was being punished and shut out right in the middle of the press conference and continued engaging with Trump as if nothing out of the ordinary was going on.

Trump has a history of doing this -- and worse.

He has literally banned the Des Moines Register from covering his events.

He banned Univision from attending his events.

He revoked The Washington Post’s credentials for a period in retaliation for a headline that he didn’t like.

He revoked Politico’s credentials for a while to punish them for an article he didn’t like. BuzzFeed -- which Trump called “a pathetic pile of garbage” during the press conference -- has been on a blacklist since June of 2015. The Daily Beast is on the blacklist and is almost always denied credentials as a result. This list isn’t exhaustive, either.

But journalists covering Trump don’t learn. Time and time again, as one outlet after another is frozen out, reporters continue to go about their interactions with Trump and his people as if nothing is wrong.

Enough is enough. Some principles are more important than competition among news outlets.

If a free press has any hope of surviving the next four years, we need the journalists covering Trump to nip this in the bud and send a clear message: If Trump blackballs one of you, the rest of you need to stand up.

Send a message to the entire White House press corps: If you see Trump blackballing an outlet, speak up and fight back.

If not, you could be next.

This campaign is now closed.