Sanders' Popularity Forces Unusual Move by AFL-CIO Chief reminds local affiliates they can't endorse a candidate By John Johnson, Newser Staff Posted Jul 3, 2015 2:16 PM CDT 146 comments Comments Democratic presidential candidate Sen. Bernie Sanders speaks at Morningside College in Sioux City, Iowa, on Thursday, July 2, 2015. (Justin Wan/The Sioux City Journal via AP) (Newser) – If you haven't been paying attention to the many, many candidates running for president, it may come as a surprise to learn that the one drawing the biggest crowds is none other than Bernie Sanders. He spoke to 10,000 enthusiastic supporters in Madison, Wisconsin, this week, which is "incredible" for this stage of the campaign, writes Matthew Yglesias at Vox. The Vermont senator's populist pitch is resonating especially well with rank-and-file union members, so much so that Politico reports on an unusual move by the chief of the AFL-CIO: Richard Trumka sent out a memo to state and local leaders reminding them that they can't endorse a candidate—only the national branch can do that. Chapters in South Carolina and Vermont already have expressed formal support for Sanders, notes Politico. The story quotes the AFL-CIO president in Massachusetts as saying that he understands Trumka had to get tough, but in the same breath he explains why the senator is such a blue-collar favorite: "Sanders has spent his life actually fighting for working people. He’s made no secret of it, and he’s used it as his mantra. And that I respect very much.” But what about Hillary Clinton? “Who? Who? Please. I mean with all respect, huh?” The Sanders camp hopes the national office will hold off on an endorsement during the primaries.