Then came 2016, which gave Mr. Trump an eight-percentage-point win in Ohio and swept in a new state representative for the district that included Nelsonville, which had been held by a Democrat for the previous eight years.

It was now held by a young Republican, Jay Edwards, who had been three years ahead of Mr. Sappington at Nelsonville-York High. He was a star quarterback who’d gone on to play linebacker at Ohio University, the scion of a prosperous local family.

Mr. Sappington was still mourning the election when, just a few weeks later, he confronted darkness of a different order. His longtime boyfriend — a gentle autodidact who had taught himself to build furniture and musical instruments when not working at Ruby Tuesday — committed suicide, at age 25.

At the next council meeting, Mr. Sappington spoke about the death, and the need for better mental health services in southeast Ohio. Jay Edwards was in the audience, as both Mr. Sappington and another council member recall, and stood up to leave in the middle of his remarks. (Mr. Edwards declined to comment on the record about that meeting or the race.)

A few months later, Mr. Sappington suffered another loss: the suicide of one of his cousins. A high school friend, a former service member , was succumbing to opiate addiction.

The gloom seemed relentless. Mr. Sappington decided the best way to fight it was to have something else to think about. Late last year, he made up his mind to run against Mr. Edwards, to reclaim the 94th House District in the Ohio Statehouse for the Democrats.

He knew it would be a challenge. He was young. He would be vastly outspent. On the other hand, the district had been blue until very recently, and 2018 was promising to be a strong Democratic year. And he could, at least, count on support from unions and national progressive groups.