S.E. Cupp is a CNN political commentator and the host of "S.E. Cupp Unfiltered," covering contemporary issues on HLN. The views expressed in this commentary are solely hers.

You might not know the name Ronna McDaniel. But do me a favor, write it down.

Because what she tweeted Wednesday night is really important.

I don't know Ms. McDaniel, and presumably you don't either. She's probably lovely in person.

But on Wednesday at 9:22 p.m. ET, Ms. McDaniel, the chairwoman of the Republican National Committee, sent THIS into the ether:

Complacency is our enemy. Anyone that does not embrace the @realDonaldTrump agenda of making America great again will be making a mistake. — Ronna McDaniel (@GOPChairwoman) June 14, 2018

"Complacency is our enemy. Anyone that does not embrace the @realDonaldTrump agenda of making America great again will be making a mistake."

Take that in.

Let me say here: I am a Republican. I've been proud of that my entire adult life, even through some of our darkest hours, even when I've departed from the party on issues like gay rights and capital punishment.

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I was proud because I believed Republican policies were better for people, yes. But I was mostly proud because we were the "party of ideas."

Liberty, limited government, low taxes, fewer regulations, law and order, family first, national security -- from Reagan on, we were the party of ideas, and Democrats were the party of identity politics.

But this Twitter threat, folks, is what it looks like when a party is out of ideas.

When the great ideas are gone, or when the leader of the party has neither affection nor use for them, all that's left behind is rank demagoguery. When you can no longer elucidate the ideas, or when they are too damaging to openly acknowledge, all you can do is simply make threats, demand loyalty.

That's what the party chair did. Out loud. In plain sight.

Where Republicans once stood on principle -- even those principles that were unpopular with the taste arbiters in Hollywood, the media and the intellectual elite -- now we stand, it seems, on Trump and Trump alone.

Mike Lofgren, a former career Republican congressional staff member who served on the House and Senate budget committees, lamented earlier this year in The New York Times:

"Where did its principles go? What became of Ronald Reagan's 'party of ideas'? One by one, those ideas were tossed aside for expediency and power -- except the tax cut. A time traveler from the Reagan era would no longer recognize the Republican Party, but most Republican politicians feel no embarrassment supporting policies they once condemned."

Indeed, even the sacred tax cut isn't enough to count as a platform.

With Republicans all too eager to table their principles for this president, here's what we know they WILL support, either directly or through tacit silence:

Ripping families apart at the border, separating mothers from their infants and children.

stated equivalence between white supremacists and those who would oppose them.

Apologism for the human rights violations of brutal dictators.

A smear campaign against the FBI and our intelligence officers.

If this is the "agenda" Ms. McDaniel insists I support, the answer is of course no. The question is, why would any Republican?

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But the party of ideas is over. Gone. No more. Instead Republicans are the party of one man, and whatever he capriciously decides he believes in that day.

As the saying goes, if you stand for nothing, you'll fall for anything. We used to stand for something. Now, just one thing. And with that, you can mark the time of death: 6/13/18, 9:22 p.m. ET. #RIPGOP