STAMFORD — Incumbent Mayor David Martin was unchallenged for the Democratic nod to run for re-election at his party’s nominating convention. Tong called Martin a “steady and serious person” and said his leadership is needed in the current political climate. For the first time in several election cycles, Democrats nominated a town clerk candidate, Lyda Ruijter, to challenge incumbent Donna Loglisci for the position of city record keeper.