Vice President Al Gore made efforts yesterday to unite environmentalists and labor unions, two crucial Democratic constituencies. Speaking in Grand Rapids, Mich., where he accepted the endorsement of the Sierra Club, Gore made a point of assuring union members in the audience that strong environmental protections go hand-in-hand with a good economy. Gore: “We’re here today to tell America that as we move toward a cleaner, safer, healthier environment, we are going to create more jobs, not fewer jobs, for American families.” Gore is aiming to earn the endorsement of the United Automobile Workers, whose leaders are unhappy with the veep’s support for global trade and suspicious of policies intended to reduce air pollution and curb global warming, fearing that they could drive up the cost of cars and hurt the auto industry.