He is still doing some campaigning as it used to exist: talking to people in early-voting states . His audience sizes often number just in the double-digits, which could be viewed as a comedown compared to the thousands that were thronging Mr. O’Rourke during his Senate race last year — including one September rally in Austin featuring Willie Nelson that drew upward of 50,000 people. Did he find this contrast deflating, a reporter asked Mr. O’Rourke after a low-key rally at Keene State College in New Hampshire?

“Oh, I’m really grateful to anyone who would forgo a perfectly fine movie or dinner date to spend some time on a Friday night with a candidate for the presidency,” Mr. O’Rourke replied, offering perhaps the only possible answer a politician could give (what candidate would admit to being “deflated?”).

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Mr. O’Rourke still manages to project earnestness with his entire body. He keeps casually dropping in his now-signature profanity because, he explained, being polite and restrained “doesn’t always express the anger o r the urgency that I feel.”

His zigzagging trajectory over the last year can be ordered into pronounced phases. Last fall — the peak of his Beto-Mania Phase — ended in a narrow loss to Mr. Cruz. Nevertheless, the hype persisted. “We did not see that coming,” Mr. O’Rourke said of the continued attention, which ushered in a new phase.

Late on election night, a couple of supporters wandered into Mr. O’Rourke’s El Paso home to commiserate. “They were just these drunk dudes in their teens who were bummed out and decided to come to Beto’s house,” Mr. O’Rourke recalled. “They just walked in and were like ‘Hey dude, we’re just so sorry you lost, can I get a selfie with you?’”

“And I was like, ‘Sure, but you can’t just walk into someone’s house like this.’ And they were like ‘Oh, I’m so sorry, I’m so sorry.’”

Mr. O’Rourke nursed his defeat, set out on a road trip and went to the dentist, live-streaming as he went. He decided to run for president. From the outset, the enterprise seemed to lack definition. He was outshone and overtaken in a crowded field of movement progressives (Bernie Sanders, Elizabeth Warren), an established elder (Joe Biden) and new faces (Pete Buttigieg, Kamala Harris) who seemed brighter than last year’s meteor. He came off shaky and overwhelmed in the first two debates. Beto-mania 2018 seemed far away.