Final answer:
The Congress of Industrial Organizations (CIO) is the organization that had significant success in organizing workers in various industries, utilizing more aggressive tactics such as sit-down strikes to achieve their goals.
Step-by-step explanation:
The organization that emphasized political activity as well as organizing activity and had spectacular success in organizing the workers of the steel, automobile, rubber, electrical, manufacturing, and machinery industries was the Congress of Industrial Organizations (CIO). John L. Lewis and other labor leaders created the CIO, which emerged as a rival to the AFL. The CIO became known for its aggressive tactics, including the famous sit-down strike by the United Auto Workers (UAW) at General Motors factories. This new federation of unions often pushed for higher pay and benefits for employees, leading to significant developments in labor rights and union contracts.