Complex sentence: The National Urban League also opposed the bill as since many AFL unions discriminated against African American workers, who were often employed as strikebreakers, it would be racially discriminatory and hinder the League's efforts to open union membership to all.
Split into simpler sentences: The National Urban League also opposed the bill as since many AFL unions discriminated against African American workers, who were often employed as strikebreakers. The League felt the bill would be racially discriminatory and hinder the League's efforts to open union membership to all.