Bernie Sanders speaking at a town meeting in Phoenix, Ariz. (Photo credit: Gage Skidmore/Flickr)

Bernie Sanders is back — kind of. A new group, Our Revolution, launched this week to continue the movement that his campaign started by raising and spending money to support “candidates in lockstep with Sanders’ ideals.” But it’s disappointing many who agreed with Sanders’ call for getting money out of politics because as a 501(c)(4) nonprofit, the group would not be required to disclose its donors.

Our Revolution’s issues page has a section devoted to “Big Money in Politics,” which decries super PACs and calls for “legislation to require wealthy individuals and corporations who make large campaign contributions to disclose where their money is going.” The page contains much of the same language that the money in politics issue page on Sanders’ campaign site did. Throughout the campaign, Sanders made campaign finance a key part of his platform, calling repeatedly for a repeal of Citizens United.

A 501(c)(4) is technically a “social-welfare organization,” and can receive unlimited, undisclosed contributions. It can spend money on elections, providing it isn’t the group’s “primary purpose,” which is usually interpreted to mean that the group can’t spend more than 50 percent of its funds on elections (but some do, and get away with it). Our Revolution will support “seven ballot initiatives and more than 100 candidates,” according to Sanders.

Kenneth Gross, a political lawyer at Skadden, Arps, Slate, Meagher & Flom, told ABC News that rules preventing partisan activity can be skirted: “It’s not unusual for a 501(c)(4) to engage in partisan activities before the election, and then they can even it out with nonpartisan activity after the election.”

Our Revolution’s launch has been rocky. The New York Times reported that eight of the initial staff of 15 have resigned following the appointment of Jeff Weaver, who was in charge of Sanders’ presidential campaign, to run the group. The former organizing director, Claire Sandberg, specifically cited her fear that the group would “betray its core purpose by accepting money from billionaires and not remaining grassroots-funded and plowing that billionaire cash into TV instead of investing it in building a genuine movement.”

Weaver has pushed back against concerns that they would rely on wealthy donors, telling The Washington Post, “There’s no reaching out to the Koch Brothers or ExxonMobil. The truth of the matter is we’re going to rely primarily on small donations.”

But without releasing the identities of contributors, it’s hard for the public to know whether that really is true. A group that decries the influence of money in politics should know that donor disclosure matters. Even as a 501(c)(4), Our Revolution could set an example for other nonprofits that spend on elections and choose to reveal this crucial information. Without doing that, it’s just another dark money group.