2020 Democratic presidential candidate Elizabeth Warren participates in the She the People Presidential Forum in Houston, Texas, April 24, 2019.

Presidential candidate Sen. Elizabeth Warren said Thursday that she supported her campaign workers' decision to form a union.

The announcement comes after CNBC reported Tuesday that nonmanagement campaign employees authorized International Brotherhood of Electrical Workers Local 2320 to represent them.

"My campaign has submitted their support to join @IBEW 2320," the Massachusetts Democrat wrote in a post on Twitter. "Every worker who wants to join a union, bargain collectively, & make their voice heard should have a chance to do so. The labor movement has long fought for the dignity of working people, & we're proud to be part of it."

Warren tweet

Presidential campaigns have not historically unionized. But organizers for Sen. Bernie Sanders, the Vermont democratic socialist, made history earlier this year by forming the first union of presidential campaign workers. That union obtained a contract last month.

Democratic 2020 contenders Julian Castro, who was housing secretary under President Barack Obama, and California Rep. Eric Swalwell, have also recognized their campaign workers' unions. Those campaigns are substantially smaller than either Sanders' or Warren's.

Steven Soule, business manager for IBEW Local 2320, said earlier this week that negotiations had not yet begun.

"We look to move to the table to come to a bargaining agreement that provides pay and benefits and working conditions that are the best in the nation," Soule said.

Democrats are vying for the support of organized labor. To date, only former Vice President Joe Biden has obtained the backing of a major union. The International Association of Fire Fighters announced its endorsement of Biden in April.