Officials with the Communications Workers of America and the AFL-CIO, the labor federation the CWA belongs to, attacked a recent Politico magazine story regarding the labor union, saying the publication was "peddling misinformation" regarding CWA's members and its political activities.

The article's author stands by the report, saying that it was simply highlighting the fact that the union represents news reporters covering the 2016 election and is itself an active player in the presidential election, having endorsed Democratic candidate Sen. Bernie Sanders.

"The story reflects the fact many reporters and editors involved in crafting the 'narrative' of political races are members of a union actively engaged in perfectly legal political endorsements and contributions. However, the media very rarely make that connection known to readers. It's chiefly a question of disclosure," said James Varney, who contributed the story for Politico. Varney is a writer for the American Media Institute, a nonprofit investigative news service.

The story, titled "Do reporters know they're giving money to Sanders and Clinton?" was published online April 5. It noted that the 700,000-member CWA is an umbrella organization whose affiliates include the 25,000-member Newspaper Guild, whose members include reporters for top media outlets such as the Washington Post, the Wall Street Journal and the New York Times.

CWA endorsed Sanders in December and has donated $13,500 to his Democratic primary campaign and another $15,000 to rival Hillary Clinton, according to Opensecrets.org. Overall, the union has donated $8.7 million to federal candidates since 2008, 97 percent of it to Democrats. Varney's story called that a "conflict of interest" since the reporters' CWA dues were indirectly benefiting the Democratic candidates.

"While a union member's dues do not represent a direct check written out by a journalist on behalf of a certain candidate or cause, they contribute to the union's financial ability to carry out all its activities. In addition, members are urged to make additional contributions to explicitly political arms of the CWA," Varney noted.

CWA President Chris Shelton slammed the report in a Sunday column for medium.com, saying the article was "filled with inaccuracies" and was "an attack on journalists' freedom of association." On Monday, the AFL-CIO forwarded the column to reporters, accusing Politico of "willful inaccuracy."

The labor groups slam Varney for not reporting that the Newspaper Guild, which has a seat on CWA's executive board, abstained from the board's vote to endorse Sanders. However, CWA's December announcement of the vote does not mention that the guild abstained, instead stating: "CWA's Executive Board voted unanimously this morning to formalize members' endorsement of Sanders."

The CWA and AFL-CIO also attack the piece for not clarifying that CWA's political action fund is funded with voluntary donations from members. "The Politico article made no distinctions between the journalists who might have contributed to CWA's Political Action Fund and the overwhelming number of those who have not. Instead, it picks on all NewsGuild-represented journalists precisely because of the candidates and public policy positions that CWA supports," Shelton wrote.

It is not clear how many Newspaper Guild members donated to the fund. The CWA's December endorsement implies that the vast majority of its members were backing Sanders. "When CWA endorses a candidate it is just the beginning. Our 700,000 members are fired up, and we are going to work overtime to elect Bernie Sanders as the next president of the United States."

Shelton was particularly incensed about a two-paragraph section comparing the union's spending to those by conservative donors the Koch Brothers and casino owner Sheldon Adelson and stating that in some cases exceeding them. He called it a "false equivalency" because the article did not include contributions to 501(c) organizations, "the preferred vehicle for billionaires like David and Charles Koch."

The Politico story has been updated with a correction: "Because of an editing error by American Media Institute, an earlier version of this article understated political donations since 1990 associated with Sheldon Adelson." The section on the Kochs is unchanged.