After last month's primary, Democratic leaders in the Bronx grew more hopeful about their chances of capturing the state Senate seat that had long been held by Guy J. Velella, the once-powerful Republican lawmaker who was convicted of felony bribery charges. In the primary, Assemblyman Stephen B. Kaufman, a Democrat, who also had the backing of the Republicans, sought to win both the Democratic and Republican nominations. But he lost both primaries, a defeat that was an embarrassment to the Republicans who had supported him. But any expectations that Democrats would easily capture the prized Republican Senate seat may have...