The Republican Party exists to serve as a storage container. It has a number of functions and roles and acts as the opposite end of the seesaw from the Democratic Party. But that's mostly ancillary, flowing from its primary purpose: to institutionalize power.

The party exists -- both parties exist -- so that candidates running every two years don't have to reinvent the wheel. So that when John Boehner leaves office, an organization is in place that can ensure that his powerful position transfers to someone of like mind. So that when there is a presidential race, candidates have networks into which they can tap and allies they can call upon. It exists to create and protect paths for its members.

The party is powerful in part because it has accrued power over a long period of time. And it's amazing how quickly that power has been co-opted.

In a speech in Salt Lake City March 3, former Republican presidential nominee Mitt Romney denounced support for candidate Donald Trump, saying Trump "is playing the members of the American public for suckers." Here are key moments from that speech. (Sarah Parnass/The Washington Post)

On Thursday, Mitt Romney once again gave a speech about Donald Trump during a presidential campaign. The last time he did so was in 2012, in Nevada, right before that state's caucuses. Then, a supplicant Romney graciously accepted Trump's endorsement for his own presidential bid.

Mitt Romney expressed his gratitude to Donald Trump for endorsing him in his 2012 presidential campaign. (C-SPAN)

Now, Romney is excoriating Trump and Trump's candidacy. He called Trump a "phony" and a "fraud" in Thursday's speech, as though the nature of Trump's character has changed significantly over the past four years. It's a bit like the scene early in monster movies when the embattled military throws everything it's got at Godzilla and Godzilla simply swats it all away.

Mitt Romney is the cornerstone of the Republican establishment, its chosen nominee four years ago and the most thoroughly representative example of what the party's power brokers hope to see in a candidate: commitment to principle, studious, respectable. In 2012, Romney fended off other candidates in the primaries because of his ability to leverage the power of the party, major donors and endorsements, and all of the other things the GOP stores in bulk in closets around its Capitol Hill headquarters.

At the time, the Trump endorsement was remarkable solely because Trump had been agitating outside of the walls of the establishment before being humiliated by President Obama and deciding against running for president. But it was also unremarkable, because this is what the party does. It asks other powerful people to give up a bit of their own power to be added to the GOP's storehouses.

The power in an endorsement or a donation always lies with the giver. Donors would give up that power because they wanted to leverage the institutional power of the party to shape the political landscape. Even if you had all of the money in the world, you probably didn't have enough to bankroll a presidential campaign. What's more, you didn't have an endorsement process and you didn't have the ability to grab media attention and you didn't have a network of loyalists.

You see where this is going, but there's a way station first.

Last month, we noted that the Internet reshaped a critical part of that relationship: the ability to communicate. A few years ago, the Koch brothers realized that they didn't need the Republican Party to build a grass-roots army and that they certainly didn't need the party to fund it. So they created Americans for Prosperity, a conservative group that in 2014 was essentially the country's third-biggest political party. It was a direct challenge to the institutional power of the Republican Party and an overt one. It mobilized communications and organizing and money -- but it essentially worked as an add on to the GOP.

It's also where Donald Trump's campaign manager Corey Lewandowski got his start.

During a town hall meeting in New Hampshire, GOP presidential candidate Donald Trump slammed 2012 presidential nominee Mitt Romney, saying that he "choked." (Reuters)

What Trump has done is revealed how little power is left in the Republican Party. Trump doesn't need donors, as he likes to brag. His dismissal of Romney's speech is the dismissal of the guy who knows he was being used. Trump, like most big donors, secretly understood that he was being used, and now he's more than happy to point it out.

Nor does Trump need the party's ability to grab media; that's a candle compared to the spotlight he can wave around the skies. One of the ways the party protected its power was by leveraging the anonymity of the candidates. So much for that with Trump. All he needed was that smooth path to becoming a Real Candidate, through the knotted fields of politics that had been trampled down by George W. Bush and Ronald Reagan and Romney before him. The party's institutional power was also deployed to protect access to those byways, keeping people like Trump off it by putting up barriers where they could. Back to the Godzilla analogy: Trump stepped right over those barriers and is now tromping potholes all over the place.

Part of Romney's objection to Trump is clearly that he thinks Trump is a boor. Part of it, too, is that Trump's positions on core Republican issues are an anathema. But perhaps Romney's biggest objection is that Romney is a product of the Republican establishment and he recognizes the threat posed by Trump.

If Trump wins the nomination -- which is more likely than not -- the Republican Party will stumble. If Trump wins the presidency, he will have enormous say in what the party looks like from top to bottom. The party will still have enough power to facilitate Senate, House, state and local races nationwide. But it will be an appendage of Trump. If Trump endorses a Herman Cain for Senate over a sitting representative who has worked his way through the system for two decades, what's the party going to do?

The paths worn down over a century, paved with contributions from donors and with routes driven by endorsers, will be handed over to Trump.

That's the party's fear. And it's a valid one.