Democracy for America has endorsed U.S. Sen. Bernie Sanders (I-VT) in the Democratic presidential primary race.

"Bernie Sanders is an unyielding populist progressive who decisively won Democracy for America members' first presidential primary endorsement because of his lifelong commitment to taking on income inequality and the wealthy and powerful interests who are responsible for it," DFA's Charles Chamberlain said Thursday in announcing the endorsement.  "Throughout his campaign, Bernie has repeatedly said that the huge problems of income inequality, money in politics, and structural racism that our country must confront are bigger than a single campaign -- they need a political revolution."

"With today's endorsement, DFA members are joining Bernie's 'political revolution' and working to take it both to the White House and up-and-down the ballot, in races coast to coast," Chamberlain added.

The progressive group, which has over 1 million members nationwide, was founded in 2004 by former Vermont Gov. Howard Dean (D), who is backing Democratic presidential frontrunner Hillary Clinton.

Sanders won DFA's presidential primary endorsement with nearly 88 percent of the vote from its members. A total of 271,527 votes were cast. As for the other two Democratic presidential candidates, Clinton pulled in 10.3 percent of the vote, while former Maryland Gov. Martin O'Malley garnered 1.1 percent.

"DFA's tireless focus on bringing people together through grassroots organizing is the best way we can fight back against the billionaires and oligarchs who have rigged our economy," Sanders said. "I also want to congratulate DFA for its principled support for grassroots democracy and for its internal democratic process. It is no secret that the founder of DFA -- my friend and fellow Vermonter former Gov. Howard Dean -- has chosen not to support my candidacy. Yet the leadership of DFA allowed a fair and free vote to take place which we won. That's pretty impressive."

Also on Thursday, Sanders earned the endorsement of the Communications Workers of America, which has some 700,000 members.