ej is likely the only communist, or communist supporter in this thread.
It is a requirement of the Communist Party USA members to join labor unions. As laid out by their "constitution".
CPUSA Constitution – Communist Party USA
SECTION 6. All Party members who are eligible shall belong to their respective labor unions. Party members will strive to build work place organization and solidarity in whatever manner possible.
SECTION 7. Members of the Communist Party shall work to strengthen the labor unions, civil rights, peace, youth, student, religious and other community organizations and social networks in which they participate. They shall promote the voice and effective participation of the working class. They shall promote unity with the allies of the working class in the course of fighting for common goals.
Unlike ej, I actually read stuff.