The problem is that while Congressional Republicans are sure that there's something scandalous about Benghazi, they've had little luck convincing anyone other than Fox News and its viewers. But to keep the momentum going — nothing sinks an agenda-driven story more effectively than when nothing new happening — they have created a feedback loop, in which Fox reports something, the Republican-controlled House holds hearings on it, and then Fox reports on those hearings. Here's this week's cycle:

On April 29, Fox reported that four officials at the State Department and CIA were being prevented from whistleblowing on Benghazi. Their lawyer, Victoria Toensing, said "people have been threatened… And not just the State Department. People have been threatened at the CIA." Toensing is half of a power couple known for leading investigations into Democrats.

On April 30, a reporter asked Obama at a press conference whether the whistleblowers had been blocked. "I’m not familiar with this notion that anybody’s been blocked from testifying," Obama said. On Fox News that night, South Carolina Rep. Trey Gowdy demanded to know why Obama hadn't taken action based on the Fox report. Gowdy said:

The president now has known for 12 hours that there was an allegation that whistleblowers are being thwarted or being silenced. So what's he done in the last 12 hours? Did he call the State Department? Did he call the CIA? ... I know he made a phone call yesterday to a basketball player. Did he make a phone call to the whistleblowers who are trying to expose the murder of four fellow Americans?

On May 1, the House Oversight Committee announced there would be another hearing into Benghazi, apparently based on the Fox report. Committee chair Darrell Issa posted a movie poster-style photo advertising the hearing, at right. (Yes, that is Issa's blurry face, with his name featured like he's the Tom Cruise of the Benghazi hearings.) The mystery witnesses would be revealed! Maybe. Utah Rep. Jason Chaffetz was reluctant to say who would speak when asked by Fox News’s Bill Hemmer. "We'll hear from people people who've got personal, first-hand knowledge about what actually did happen in Benghazi," Chaffetz said, but wouldn't say who that was. The whistleblowers? Hemmer asked. "I think they will be appearing -- some of them, some of them. Again there's a host of them…. there are different processes, there are different levels at which they've come in and spoken with us."

None of this has clarified what happened in Benghazi. If the whistleblowers feel free to leak their existence to Fox News, why don't they also leak what they know? So far, the results have been disappointing. Fox reported Tuesday that the "mastermind" of the Benghazi attacks "is walking free in Libya." The secret source says the U.S. is "sitting on" the information, and that the family of those killed would be really mad if they knew that. But it doesn't explain why the U.S. would sit on that info. For fun? It's not like the government has stopped investigating the case. The same day, the FBI released photos of three men who were on the ground during the attacks. CNN reported that law enforcement thinks three or four members of al Qaeda in the Arabian Peninsula were involved, though it's not clear whether they were sent to Libya or were already there and saw an opportunity.