In an unusually strong gesture of blue-green solidarity, 10 major labor unions called on presidential candidates yesterday to back a decade-long, $300 billion research plan to boost energy efficiency, reduce U.S. dependence on foreign oil, and preserve jobs. Known as the Apollo Project, the plan calls for the promotion of hybrid and hydrogen cars, energy-efficient factories and appliances; more financing of high-speed rail projects; expanded use of solar and wind power; and the creation of manufacturing jobs to replace some of the 2 million lost in recent years. Proponents of the plan hope it will forge better ties between the labor and environmental movements, which are at odds as often as they are allied. Its backers include the steelworkers and autoworkers unions, as well as the United Mine Workers, the Service Employees International Union, the International Association of Machinists, and the International Brotherhood of Electrical Workers.