Clearly frustrated by a series of gaffes, Benghazi committee chairman Trey Gowdy on Sunday told fellow Republicans to “shut up” if they weren’t directly briefed on the committee’s activities. The Benghazi committee is heading into a seminal week for its work, with a long-anticipated hearing featuring former secretary of state Hillary Clinton on Thursday.

Republicans on the investigative committee have been stymied by a series of public statements alleging that the committee’s purpose is political: to cut down the poll numbers of Clinton and her presidential campaign.

“These are three people who don’t have any idea what they’re talking about,” Gowdy said on CBS’s Face the Nation. “Four dead Americans is reason enough [for an investigation].”

GOP Majority Leader Kevin McCarthy earlier made comments to that effect, and Rep. Richard Hanna said the committee was “designed to go after” Clinton. A former committee staffer has also complained that the investigation was improperly focused on Clinton rather than on the 2012 attacks that killed four Americans in Libya.

Neither McCarthy nor Hanna has asked for any updates on the committee’s activities, Gowdy argued, and the staffer hasn’t been involved with the committee’s affairs since he left in June.

“I have told my own Republican colleagues and friends, ‘Shut up talking about things you don’t know anything about,’” Gowdy said. “Unless you’re on the committee, you have no idea what we’ve done, why we’ve done it, and what new friends we have found.”

—Tim Mak