Whoa, Ted Cruz. It was hard to predict what he would do when he agreed to speak at the Republican National Convention despite not having endorsed Donald Trump, but fireworks would not have been my first guess.

While other major Republican figures have been both unwilling to alienate Trump supporters and unwilling to embrace the man himself, Cruz left it all out on the stage in Cleveland on Wednesday night. The man who came closer than any to challenging Trump in the primary gave a spirited speech about America’s great tradition of freedom and the proud history of the party. Yet he steadfastly refused, even amid a chorus of boos, to endorse Trump. The boos seemed to energize Cruz. They definitely energized what remains of the Never Trump wing of the GOP.

It’s one thing for Republicans who are old and out or almost out of politics—like the Bushes, Mitt Romney, even John McCain—to speak out against Trump and stay away from the convention. It’s a much tougher road to navigate if you’re part of the future of the party. A select few have tried. A handful came up with clever excuses to stay away from Cleveland. Illinois Sen. Mark Kirk—the first politician to un-endorse Trump—joked that he had to get his hair done. Arizona Sen. Jeff Flake said he had to mow his lawn.

Others have mostly depressed those of us who were hoping to see some spine. South Carolina Gov. Nikki Haley declined an invitation to speak at the convention but showed up in Cleveland and talked about the importance of beating Hillary Clinton without mentioning Trump. Paul Ryan, as speaker of the House, is in the worst position, and I don’t envy him. He initially refused to endorse Trump and held out for a whole month. But instead of using his leadership position at the convention to do something bold, he gave a speech embracing Trump. I had to change the channel.

Marco Rubio took perhaps the strangest tack, appearing at the convention only by video. His brief spot looked like a cross between a campaign ad and a hostage video. In hindsight, it seems like a silly move. Instead of looking bold for refusing to be in Cleveland, he looked timid.

They all paled in comparison to Cruz. For those of us who watched the delegate fight on Monday with the tiniest bit of hope that something exciting would happen, that the RNC might at least acknowledge that there was a rift in the party, only to be disappointed, Cruz’s speech will end up as the high point in the convention.

Read more Slate coverage of the 2016 campaign.