The U.S House Ethics Committee will take a deeper look at an ethics complaint against Rep. Ben Ray Luján.

Rep. John Conyers, D-Michigan, and Michael Collins, the chief of staff to Rep. John Lewis, D-Georgia, are also under review by the watchdog panel.

The committee did not say why the three are under investigation, but Luján’s office said his comes from a complaint from a conservative group, the Foundation for Accountability and Civic Trust.

The committee noted that the announcement of the extension of the matter “does not itself indicate that any violation has occurred, or reflect any judgment on behalf of the Committee.”

According to Luján, the complaint stemmed from a sit-in by House Democrats on the House floor in which Democrats sought to force a vote on legislation that would bar those on the federal no-fly list from purchasing guns.

A spokesman called the complaint “frivolous” and “without merit” and that it was “filed by a highly partisan outside group about activities during the sit-in last year.”

The complaint noted that Luján sent an email asking for contributions, and that it “included a photograph of the House floor that credited ‘video provided by House Television.’” The House’s Official Code of Conduct says representatives cannot use House Television images “for any partisan political campaign purpose.”

The organization also said the sit-in itself was part of the representatives’ official capacity and so could not be fundraised off of.

Luján has become one of the more high-profile Democrats in recent years since becoming chair of the DCCC.

The deadline for the ethics committee to take any action is Aug. 9.