A Cincinnati streetcar project, embroiled in controversy in recent years over cost overruns and management, faces an uncertain future after Tuesday's election ushered in a new mayor who vowed to halt the project that has tied up $148 million of city funds.

Mayor-elect John Cranley, a Democrat who ran on a platform of fiscal responsibility that included stopping the project, won about 58% of the votes tallied, according to unofficial results from the Hamilton County Board of Elections. He beat out current Vice-Mayor Roxanne...