Democratic presidential hopeful Bernie Sanders got his biggest union endorsement thus far Thursday as the American Postal Workers Union (APWU) announced its support for his candidacy.

Unions aren’t just major financial contributors, they also rally hoards supporters. As a result, Bernie and his Democratic rival Hillary Clinton have competed for their support. The latest endorsement represents a huge victory for the Vermont socialist. The union represents 200,000 employees and is affiliated with the AFL-CIO.

“Politics as usual has not worked,” APWU President Mark Dimondstein said in a statement. “We should judge candidates not by their political party, not by what they say, not by what we think they stand for, but by what they do.”