President Obama’s top campaign lawyer filed a federal complaint on Tuesday demanding that Crossroads GPS, a nonprofit advocacy group led by the Republican operative Karl Rove, reveal its donors, Reuters reports.

Officials of Crossroads, which is registered with the Internal Revenue Service as a 501(c)(4) “social welfare” organization, have said that it and an affiliated super PAC would spend $300-million this year to help elect G.O.P. candidates. Unlike super PACs, 501(c)(4) groups are not required to disclose contributors as long as their activities are not primarily political.

In his complaint to the Federal Election Commission about Crossroads GPS, Robert Bauer, an attorney for the Obama campaign, wrote that “There has never been any doubt about its true purpose: to elect candidates of its choice to the presidency and Congress.”

Jonathan Collegio, a spokesman for Crossroads, said the complaint represents “a goofy sideshow” until the president’s campaign takes a similar stance on Priorities USA,” a Democratic 501(c)(4) organized by former Obama aides.