Janitors who are members of the Service Employees International Union Local 105 voted Tuesday to authorize a strike across metro Denver if negotiations with 17 cleaning contractors don’t lead to acceptable terms. The contract that expires July 28 covers about 2,400 people who work in approximately 1,500 buildings. Stephanie Felix-Sowy, president of SEIU Local 105, said union members’ main priorities include a livable wage and a solution to concerns about the workload. “Workload meaning additional workload being placed on our members while hours are being cut oftentimes,” Felix-Sowy said. Eva Martinez was among several union members casting ballots in a downtown plaza and rallying support from pedestrians and drivers.