As metaphors for the Trump-led Republican Party go, it's difficult to beat Rep. Todd Rokita's new ad in the Indiana Senate race.

In 30 seconds, the Republican congressman from Indiana discusses no policy issues and says basically nothing besides “I will support Trump the most,” before throwing on a Make America Great Again hat for emphasis.

The ad, titled “MAGA,” is a remarkable little window into how at least one candidate thinks you win in today's GOP, and Rokita hopes it's his ticket to the Republican nomination to face Sen. Joe Donnelly (D-Ind.) next month.

Here's a quick transcript:

I'm Todd Rokita, and here's the truth: We're not going to beat Joe Donnelly with a RINO [Republican in name only].
Mike Braun? He's a lifelong Democrat. He voted for Obama or Hillary. Wow.
And Luke Messer? He plotted with the Never Trumpers to steal the nomination from President Trump. You've got to be kidding me.
I'm Todd Rokita, and I'll proudly stand with our president and Mike Pence to drain the swamp.

It's hardly unprecedented for a candidate to argue that he is more supportive of his party's president than his primary opponents. In fact, as the New York Times noted in a story on the race this week, Rokita and his opponents have basically turned the primary into a competition over which candidate is the Trumpiest.

But it is a bit of a sign of the times for the Republican Party. Trump has rendered many policy positions negotiable — even with himself — and has turned a Republican Party that was all about conservative purity earlier this decade into one that is more about Trump purity. It's a party built on personality whose base has stood by Trump, even as he has shrugged off an antagonistic foreign power's incursion into U.S. elections. It's a party that almost instantly and universally dismisses every Trump-inspired controversy as unimportant and a media creation — even “fake news.”

Sen. Bob Corker (R-Tenn.), who has made nice with Trump recently after decrying the White House as an “adult day-care center” a few months ago, offered this apt quote recently about Trump's base of support.

“It’s more than strong; it’s tribal in nature,” Corker said, adding: “People who tell me, who are out on trail, say, 'Look, people don’t ask about issues anymore. They don’t care about issues. They want to know if you’re with Trump or not.' ”

Rokita must be sensing the same thing.

The problem with being the most “with Trump,” though, is that what it requires can change depending on the day. Trump isn't just a political novice — he's a chameleon. That may sound harsh and negative, but it's objectively true and even a testament to Trump's ability to hold his base almost by sheer force of personality. The prevailing ethos of Trump's presidency isn't conservative policies so much as “Trump will take care of it, and don't worry about the details.”

There's no question as to why candidates such as Rokita want to be associated with Trump. But just at its core, Rokita isn't subscribing to any specific policies; he's subscribing to supporting a president who might do all kinds of things he never expected. Yet Rokita has wagered that the most important thing is that he assures people he'll be along for the ride.