Bernie Sanders wins his largest union endorsement of campaign

Democratic presidential candidate Sen. Bernie Sanders, I-Vt., has won his biggest labor union endorsement to date.

The Communications Workers of America formally backed Sanders after a vote by the 700,000-member union of technology and telecommunications workers showed a "decisive majority" supporting his primary bid. The union vowed to pour resources into his campaign.

"Their endorsement is not just a paper endorsement," said Sanders, at a joint Washington press conference with the union. "We're going to have thousands of people on the ground knocking doors, making phone calls and helping us."

The communications workers are the third union to endorse Sanders.

Many more unions have endorsed Clinton, although in some cases groups of these unions’ rank-and-file members have openly supported Sanders. Last month, the two million member Service Employees International Union, the primary backer of the Fight for $15 fast-food worker strikes around the nation, endorsed Clinton. Days later, its New Hampshire affiliate publicly dissented and endorsed Sanders.

"What I would have hoped is that unions who believe in democracy would have done what the CWA did, which is really create a wide-open process," said Sanders. "We would have a lot more national union support than is currently the case."

Labor for Bernie, an independent group of rank-and-file union members who support the Sanders campaign, said in a statement that it hopes other unions will follow communications workers’ lead.

"Thousands of [communications workers union] members across the country took part in a months-long democratic selection process," said Rand Wilson, a volunteer for the group and a staffer at a Service Employees International Union local in Massachusetts. "We hope the many unions that haven't yet made an endorsement decision will engage in a similar process of rank-and-file engagement."

Thursday’s union endorsement was widely expected. The communications workers’ former president, Larry Cohen, has been an unpaid labor adviser to Sanders' campaign and a vocal opponent of the Trans-Pacific Partnership trade agreement, which Sanders has assailed as detrimental to middle-class jobs and wages.

"We will use whatever we need" to drive the campaign, said the union’s current president, Chris Shelton. "We will use our PAC money. If Bernie doesn't want to take it, ok, I respect that, but we'll use it to make sure we'll do everything we can to get the vote out."

Sanders had previously said he would not accept super PAC money for his campaign.

The Communications Workers of America decided to back Sanders based on a vote by its members, rather than a decision by its leadership. Unlike some other unions, it did not ask Sanders to answer a questionnaire or sit for interviews with its executive board. The communications workers’ leadership instead helped develop questions for a live interview conducted at an AFL-CIO summer meeting.

"It would have been an empty endorsement coming from me," said Shelton. "He could have gotten 22 votes from our executive board. This way, he will have 700,000 votes."

Sanders’ team also announced Thursday it had received two million financial contributions from supporters as a sign of the candidate’s grassroots fundraising success. The campaign said it has raised more than $3 million since Monday.

Al Jazeera and The Associated Press