What does it means to vote "union"?

 For so many working families, voting their jobs and their unions will be at the top of their voting priority lists. But what does it actually mean mean to vote "union"?

Union members across the country must make their voices heard at the ballot box. For public union members, this means supporting candidates who support public service and public pensions; it means standing with candidates who support your union contract and your right to bargain; and it means choosing those who fight for affordable health care and an economy that works for working people, not billionaires.