Who are the groups that try to improve pay and working conditions by organizing workers to refuse to work until employers met their demands?

The groups that aim to improve pay and working conditions by organizing workers to refuse to work until employers meet their demands are typically labor unions and worker advocacy organizations. These entities mobilize workers to engage in strikes or work stoppages as a means of negotiating better wages, benefits, and working conditions. They play a crucial role in collective bargaining and promoting workers' rights. Additionally, grassroots movements and solidarity networks can also support these efforts.