Sen. Elizabeth Warren’s (D-Mass.) presidential campaign officially unionized on Thursday, becoming the fourth presidential campaign to do so.

“My campaign has submitted their support to join @IBEW 2320,” Warren announced 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.”  

My campaign has submitted their support to join @IBEW 2320. 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.

— Elizabeth Warren (@ewarren) June 6, 2019

{mosads}Rep. Eric Swalwell (D-Calif.) announced in April that his campaign would recognize a union formed by staffers as members of the Teamsters union.

The campaigns of Sen. Bernie Sanders (I-Vt.) and former Housing and Urban Development Secretary Julián Castro unionized in May.

Because it is unclear if Swalwell’s campaign struck a deal with staffers, Sanders’s campaign is thought to be the first to officially unionize.

The same week that Sanders’s and Castro’s campaigns unionized, former Vice President Joe Biden’s campaign said they would “welcome it” if its staff formed a union.