LOUISVILLE — Stephon Harbin leans Democratic but says he resents being pigeonholed in one party. House Speaker Paul Ryan, for instance, strikes an intellectual chord with him despite being a Republican. For Mr. Harbin, following politics is part of a civic duty to make his city a better place.

“The only way it’s going to change is if you’re instrumental in the change. It has to be a team effort,” Mr. Harbin said recently as he sat in the living room of his bungalow in Louisville’s California neighborhood, southwest of downtown. “I’d run for office, if I could.”

But Mr. Harbin, who is 47, cannot run for office. Twenty-nine years ago, he was arrested for selling cocaine — a scheme, he said, to pay for his freshman year in engineering school at the University of Louisville. The ensuing felony conviction, and another that followed two years later, stripped him of his political rights for life.

His first arrest came when he was 18, and he was convicted barely two weeks before Election Day. “I never had the opportunity to vote,” he said.