Republicans accuse the Obama administration of misleading the American people about a terrorist attack weeks before the presidential election by blaming the assault on protests touched off by an anti-Islam video. An independent investigation and a bipartisan Senate Intelligence Committee report earlier this year blamed inadequate security and faulted the State Department.
House Speaker John Boehner, R-Ohio, said the Obama administration has not been forthcoming.
"They owe the American people the truth. And when it comes to Benghazi, we've got four Americans who are dead. And their families deserve the truth about what happened, and the administration refuses to tell them the truth," Boehner told reporters at a separate news conference.
McKeon said five committees are investigating. His panel and members of the House Oversight and Government Reform Committee interviewed retired Gen. Carter Ham, who headed the Africa command, for nearly seven hours on Wednesday. McKeon said he was told lawmakers heard nothing new in the testimony by Ham, who has spoken to investigators at least six times.
"We have been working on this for a long time. We issued a preliminary report," McKeon said. "At some point, when we run out of people to talk to, or we run out of people to talk to two or three times, at some point, we think we'll have as much of this story as we're going to get and move on."
Democrats have called for an end to the investigations, arguing that Republicans are on a futile search for information to embarrass the Obama administration. Republicans reject those calls and insist there are numerous unanswered questions and that they owe it to the families of the dead Americans to investigate.
The Armed Services Committee's interim report released earlier this year said the military's response "was severely degraded because of the location and readiness posture of U.S. forces, and because of lack of clarity about how the terrorist action was unfolding. However, given the uncertainty about the prospective length and scope of the attack, military commanders did not take all possible steps to prepare for a more extended operation."
The Senate Intelligence committee report described the military's actions. One unarmed Predator drone was diverted for surveillance, a seven-man security team with two Defense Department members flew from Tripoli to Benghazi to evacuate Americans and then Defense Secretary Leon Panetta ordered two Marine anti-terrorism security teams from their base in Rota, Spain, to Libya.
Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff, and Panetta have testified to Congress that the lack of intelligence about what was happening on the ground in Benghazi made it difficult to send in jet fighters or other aircraft.