What is the primary purpose of a labor union?

The primary purpose of a labor union is to protect workers' rights and interests. Labor unions are organizations formed by workers to collectively bargain with employers on various issues including wages, working conditions, benefits, and job security. Through solidarity and collective action, unions strive to ensure that workers have a voice in the workplace and can advocate for fair treatment and equitable compensation. This focus on protecting and advancing the rights of workers is fundamental to the mission of labor unions, making this answer the most accurate in the context of the question.

While competing with management and endorsing candidates can be secondary activities for some unions, they are not the main purpose of their existence. Additionally, unions are not primarily aimed at increasing profits, as their focus is more on improving the work environment and ensuring fair labor practices for their members.