Beto O’Rourke joined Stephen Colbert on The Late Show Wednesday night, but before he took the stage, the host made sure his audience knew everything they needed to about Ted Cruz’s Democratic opponent.

“Beto is running in Texas against incumbent senator and man whose campaign staff is definitely watching this show right now, Ted Cruz, because it is close, which is scaring Republicans,” Colbert said. This summer, Texas Republicans practically begged President Donald Trump to campaign for Cruz. “You know it’s bad when you need backup from a man with a 36-percentapproval rating,” he added. “Their backup plan is a celebrity endorsement from the herpes virus.”

“Here’s how scared Ted Cruz is of Beto O’Rourke,” Colbert continued. “He bought ads on my show tonight to counter his interview.” It’s true. As the Houston Chronicle reported this week, the Cruz campaign bought ads on Wednesday night’s Late Show across several Texas media markets.

The host also mocked the Texas GOP’s personal attacks on O’Rourke, including one in which they posted a photo of O’Rourke from his punk rock days with the caption, “ Maybe Beto can’t debate Ted Cruz because he already had plans…”

“Yes, his plans were being smoking hot in a naughty but approachable sort of way, like your best friend’s older brother who smells like weed and listens to Radiohead,” Colbert said. “Read us your poems, Beto!” Another Cruz ad highlights O’Rourke dropping a few F-bombs. “Beto is a dirty-minded potty mouth,” the host said. “You must protect the values of Texas, and vote for the man who likes threesome porn on Twitter.”

Later, when O’Rourke sat down with Colbert, he charmed the Late Show audience with his unabashedly progressive positions, including his opposition to Trump’s border wall. Asked what he makes of the president “joining forces” with his one-time enemy Cruz against him, O’Rourke said, “The people of Texas are more than a match for President Trump or for politics as usual.”

“People are coming out at this moment of truth,” he said. “They’re going to help us decide as a country, are we a nation of walls? Will we ban all Muslims or all people of one religion? Will we describe the press as the ‘enemy of the people’? Will we take kids away from their parents when they’re trying to claim asylum, fleeing from the most brutal countries in this hemisphere, if not the planet?”

“Or are we going to be defined by our ambitions, the big things that we want to do, going from the least-insured state in the country to the one that leads on universal, guaranteed, high-quality health care for everyone?” he continued. “A state that values public education and pays their teachers accordingly and allows them to teach to a child instead of a standardized test? And this diverse state, the most diverse city in the country, Houston, Texas, could we lead on rewriting our immigration laws in our own image, reflecting our experience? We can do all of those things.”

“We are not running against anyone or anything or any other political party,” O’Rourke concluded. “We are running for this country, and I am so excited to be a part of it.”