It wasn't the first time Donald Trump interrupted Ted Cruz. But it might have been the most over-the-top—literally.

Today, hours before he is to take the stage at the Republican National Convention, the Texas Senator arrived in Cleveland to rally his primary season supporters at a waterfront thank-you party. In many ways, it was exactly like any stump speech Cruz has delivered over the last year: oversized cowboy hats, Texas flag t-shirts, free novelty cups bearing Cruz's name. Except just as Cruz uttered the words, "Our party now has a nominee," a massive Trump plane soared overhead. "That was pretty well orchestrated," Cruz said, laughing off the ominous coincidence.

But if Cruz had planned to use that moment to talk about unifying around the nominee, the crowd stopped him short with their chorus of boos. Cruz's true red-white-and-blue supporters were glad he didn't endorse Trump and hope he doesn't tonight. Many of them still can't forgive Trump for those Heidi Cruz tweets.

"He maligned his wife," says Illinois delegate James Kammer of Trump, referring to a crass meme the GOP's presidential nominee retweeted that demeaned Heidi Cruz's appearance.

"If you're married and another man trashes you publicly, what would you expect your husband to do?" Kammer says "Think about it that way."

Kammer says he plans to vote in November, just not for president. "I'm going to leave that space blank on the ballot," he says. If Cruz does endorse Trump, Kammer adds, that would diminish his family's support for Cruz in the future. "We're not going to ever endorse someone or work for someone who endorses Trump," he says.

Kammer wasn't the only one who felt that way. "I don't want him to say, 'Please vote for Trump,'" says Lillian Nolan, an alternate delegate from Fon du Lac, Wisconsin. And yet, she said, despairingly, "There's no plan B. I just think it would be hard for me to sleep at night right now to vote for Trump."

All eyes will be on Cruz tonight as he takes the stage at the convention, where it's still unclear whether or not he'll signal support for his one-time adversary. (Update: He didn't.) But if his waterfront rally is any indication, Cruz might have a better chance of securing his political future if he doesn't endorse Trump. Cruz's base views his steadfast, uncompromising conservatism as his strength, and they fear a Trump endorsement could damage his future in the Republican party.

And make no mistake: Cruz plans to have a future. Amid chants of "2020! 2020!" Cruz spoke much like he had on the stump. He stuck around for nearly an hour after his talk to shake hands and pose for selfies with supporters, several of whom had badges around their necks with a picture of Trump and the word "Loser" emblazoned on it. Complete with a live band blaring country tunes, the event had all the trappings of a campaign stop. And maybe that's what it was, just four years early—or a year too late.