Sen. Elizabeth Warren Elizabeth WarrenDimon: Wealth tax 'almost impossible to do' CNN's Don Lemon: 'Blow up the entire system' remark taken out of context Democrats shoot down talk of expanding Supreme Court MORE'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

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Rep. Eric Swalwell Eric Michael SwalwellSwalwell calls for creation of presidential crimes commission to investigate Trump when he leaves office 'This already exists': Democrats seize on potential Trump executive order on preexisting conditions Swalwell: Barr has taken Michael Cohen's job as Trump's fixer MORE (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 Bernie SandersOutrage erupts over Breonna Taylor grand jury ruling Dimon: Wealth tax 'almost impossible to do' Grand jury charges no officers in Breonna Taylor death MORE (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 Joe BidenBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Democratic groups using Bloomberg money to launch M in Spanish language ads in Florida Harris faces pivotal moment with Supreme Court battle MORE's campaign said they would "welcome it" if its staff formed a union.