“The too-isms always followed him,” said Tom Sheridan, a consultant in Washington who has worked with Congress to expand legal protections for people with AIDS and disabilities. “He was too young, too straight-acting, too boring, too inexperienced because he was mayor of a city that was too small.”

To many who felt a sense of empowerment from his campaign, though, those misgivings felt disconnected from their reality.

Mr. Buttigieg described the gratitude and optimism he often encountered when he was traveling the country, and acknowledged it was so powerful it took him aback at first. “Even I thought, ‘OK, maybe this is not all that much of an event,’” he said in an interview last year.

Strangers would approach him and try to convey how much it meant to see someone so public and so prominent talk about his experience as an L.G.B.T. person. One was just 9, a boy in Denver who told Mr. Buttigieg at a rally a few days before he dropped out of the race, “I want to be brave like you,” and asked, “Would you help me tell the world I’m gay, too?”

Sometimes they were much older, like the flight attendant who was so overcome with emotion when he encountered Mr. Buttigieg at an airport that he was unable to speak. “He just made eye contact and came to the point of tears,” Mr. Buttigieg recalled. “And then walked off not knowing what else to do.”

Even in 2020, part of the paradox of running a successful campaign as an openly gay man meant that his orientation could not define him to voters who might not fully accept it. He understood this, and ran his campaign in a way that always sought equilibrium. The protective armor against his sexual orientation seemed in many ways to be his résumé. He was “Mayor Pete” the Rhodes Scholar, Navy veteran, pianist and technocrat conversant in eight languages.