Sen. Bernie Sanders scored a major endorsement for his bid in the Democratic presidential race on Thursday from the Communications Workers of America (CWA) union.

CWA officially endorsed the Vermont senator Thursday morning at their headquarters in Washington, D.C., making it the biggest labor group to back Sanders thus far.

Although the union did not endorse a candidate in the 2008 Democratic primary between Clinton and Barack Obama, it announced in August that it would allow its members to vote for their favorite candidate in the primary. The decision to support the self-proclaimed "democratic socialist" was then made after the majority of members voted in an online poll in September, reports CNN.

"CWA members endorsed Bernie Sanders because he is the candidate who is talking about real solutions to make our economy fair again. Politics as usual has gotten working people nowhere. It's time for real change. That's what CWA members are saying, loud and clear," CWA President Chris Shelton said in a statement sent to Latin Post. "Our members are ready to do what it takes to elect Bernie Sanders as the next president of the United States."

The powerful group boasts about 700,000 members across the U.S. and Canada and more than 300,000 active and retired members in states that hold primaries and caucuses before April 1.

"Brothers and sisters, let me thank the 700,000 members of the Communications Workers of America for their strong support," Sanders said. "For decades you've been fighting for the rights of working families and I'm so proud today to be with you in that fight."

Back in June, CWA's former president Larry Cohen stepped down to join Sanders' campaign as a top labor adviser.

Despite his career-long support behind unions, Sanders has failed to secure national union endorsements. On the other hand, Democratic front-runner Hillary Clinton has racked up 18 national union endorsements, which represent 12 million workers in total. The Service Employees International Union, the National Education Association and the American Federation of State, County and Municipal Employees are just a few of the major unions who have sided with the former secretary of state.

Last week, the Working Families Party, a nationwide coalition of labor and progressive groups, officially endorsed the independent senator after the majority of its members voted for him in an online poll.

Sanders also released a video touting his over 2 million campaign contributions from individual supports. Watch the video below: