One thing we’ve gotten used during the presidential campaign of Donald Trump is the the presence of huge (sorry… YUGE) crowds at his rallies. It’s been one of the dominant features in all the earned media he receives and keeps the networks lining up to cover his events even as he insults them to their faces. We’re also accustomed to the occasional protesters who show up and wind up being quickly escorted from the venue. But one thing we definitely do not see at these huge events is widespread booing and catcalls directed at Trump himself from his army of generally loyal fans. And yet, that’s exactly what happened in Myrtle Beach, South Carolina this weekend. Let’s go to the video.

So what did Trump finally do to turn his own crowd against him? From the context in the video there seems to be only one explanation. He went after Ted Cruz pretty hard and the audience did not appreciate it. (NBC News)

Among conservatives, Donald Trump can typically do no wrong — until he attacks Ted Cruz.

On Saturday, Trump drew boos from a grassroots conservative crowd during remarks at the South Carolina Tea Party Coalition Convention for his attack on Cruz’s previously undisclosed loans.

“You give a campaign contribution to Ted Cruz, you get whatever the hell you want,” he said, before boos erupted from the crowd.

Trump went on as the boos grew louder: “Say whatever you want, it’s okay, he didn’t report his bank loans. He’s got bank loans from Goldman Sachs, he’s got bank loans from Citibank, folks, and then he acts like Robin Hood?”

I don’t know if Trump takes something away from this encounter and changes up his strategy or not, but he’s got plenty to think about. He can attack the Democrats (obviously) and the crowds go wild. He can go after the media in the most scathing ways and his supporters will join in with his withering criticism. He is also free to go after all of the establishment GOP candidates with insults and barbs, calling Jeb Bush low energy or Chris Christie a liberal, and the faithful will lap it up like milk from a saucer. But his anti-establishment base seems to like Ted Cruz and they don’t care to see him get muddied up at a Trump rally.

This shouldn’t be too surprising. Trump and Cruz are as close as you’d get to natural allies in this race, even as they battle each other for first place in Iowa. Donald Trump is bashing down the gates of the establishment GOP from the outside even as Cruz has spent several years setting it on fire from within. The real secret to the success of both men thus far has much less to do with their specific policy proposals and everything to do with knocking over the apple cart which conservatives now view as being full of rotten fruit.

It sounds like the crowds are picking up on this, though whether it shows up in their respective poll numbers remains to be seen. For months now, the “bromance” between the two seemed to be a winning formula. The Trump / Cruz blanket fort was a fairly safe space and each of their supporters seemed to at least respect the other candidate no matter which they were supporting. But now Mom and Dad are fighting and the kids aren’t alright.

John Hawkins seems to find the entire situation bewildering.

This is confusing for two reasons. First, who cares if Ted Cruz has loans and didn’t report them? Whatever, right? Secondly, why do people boo what’s true?

On the one hand, this should have been predictable. Trump attacks anyone who either begins to rise in the polls or raises a lot of money, as well as anyone who comes after him first. Cruz qualifies on two of those fronts at least. As to the particular issues he’s hitting him on… meh. I’ve written about the entire birther thing here before and I find it an empty threat, devoid of any interest beyond the positive outcome of having SCOTUS resolve the whole “natural born citizen” thing once and for all. As to the loans, we covered that here as well. It’s a minor foot fault at best, with some money being stuck in the wrong column on a spreadsheet.

But Trump needed some breadcrumb to go after the Texas senator on, and that’s what presented itself. The question now is whether or not we’ll see Trump back off on the attacks or at least soften them a bit. Cruz seems to remain quite popular with Trump’s base of support and if his fans start drifting away or getting turned off it wouldn’t be shocking if such a turn of events resulted in a direct benefit for Ted Cruz.