"We can not just support unions with words, we must back it up with actions".
Democratic 2020 U.S. presidential candidate and U.S. Senator Bernie Sanders (I-VT) takes the stage at a campaign rally in Concord, New Hampshire, U.S., March 10, 2019.
The staffers will be represented by the United Food and Commercial Workers Local 400, which said that anyone below the rank of deputy director would be eligible to join the bargaining unit.
Earlier this year, Sanders apologized to female staffers on his 2016 presidential campaign who said they had experienced sexual harassment from male staffers. The New York Times reported allegations of unwanted sexual advances, as well as pay inequity.
Mark Federici, president of Local 400, said in a statement he hoped "this breakthrough serves as a model for other presidential campaigns, as well as party committees and candidates for other offices". In card check, union organizers ask workers to sign cards affirming that they support a union.
Mr. Sanders, 77, announced last month that he will seek the Democratic nomination to compete against Mr. Trump in the next presidential race, making him among the latest additions to an already lengthy list of White House hopefuls.
The campaign added that employees had made a decision to unionize through a card check system, in which employees sign authorization slips consenting to being represented by a union.