Senator Bernie Sanders of Vermont secured two key endorsements on Thursday as he solidified his place as the main challenger to Democratic frontrunner Hillary Clinton.



Sanders received the backing of Democracy for America (DFA), a progressive activist group with roots in Howard Dean’s losing 2004 presidential campaign, as well as the Communication Workers of America (CWA), one of the largest labor unions in the United States.

The DFA endorsement comes after the group held an online vote to determine which candidate it would support. Of the more than 271,000 DFA members who cast a ballot, 87.9% of those participating backed Sanders. Clinton received the support of only 10.3% of DFA’s members, and longshot Martin O’Malley got 1.1% of the vote.

The endorsement from the group marks the further consolidation of Sanders’ support among the progressive wing of the Democratic Party. DFA, formed in the wake of Dean’s failed 2004 campaign, had previously been an active supporter of the effort to draft Elizabeth Warren to run for the Democratic nomination.

This endorsement – combined with that of CWA, which has 700,000 active members – gives Sanders’ campaign a much needed boost with only 45 days left until the crucial Iowa caucuses. While the senator from Vermont has consistently drawn large crowds and recently announced that he had received 2 million campaign contributions, he lags behind Clinton in national polls as well as in Iowa.