Top Republicans blasted Attorney General Eric Holder on Tuesday after reports surfaced that he might have known about the controversial “Fast and Furious” gun-tracking operation earlier than he previously claimed.

Sen. John McCain (R-Ariz.) tweeted, “What part of Q, ‘When did you first know about the program known as Fast and Furious?’ didn't AG Holder understand?”

McCain has asked for a Senate hearing into the operation.

Rep. Darrell Issa (R-Calif.), who is conducting the inquiry as chairman of the House Oversight Committee, retweeted McCain's Twitter post, along with links to news reports. Issa has used Twitter extensively to push for transparency during his committee’s ongoing investigation into the Bureau of Alcohol, Tobacco, Firearms and Explosives operation that might have led to the death of a Border Patrol agent.

Two other Arizona Republicans, Reps. Ben Quayle and Trent Franks, also took interest in the story, with Franks tweeting a link to a conservative blog post about Holder.

The gun-running operation took place in the Southwest, and has consequentially been a central issue for congressmen from that region.