The U.S. Consulate in Benghazi is seen in flames during a protest by an armed group said to have been upset over a film being produced in the United States about Islam.
A top Republican on Sunday said he expected more witnesses to step forward with information about last year's deadly attack on a U.S. mission in Benghazi and how President Barack Obama's administration responded to the unfolding events.
"I do think we're going to see more whistle-blowers. I certainly know my committee has been contacted," Rep. Mike Rogers, chairman of the House Intelligence Committee, said in an interview on "Fox News Sunday."
Last week, Republican charges that the White House covered up details of the Sept. 11, 2012, attack gathered more steam after former U.S. diplomat Greg Hicks told lawmakers he believed more could have been done to stop the assault by suspected Islamist militants.
Hicks, the second in command at the U.S. Embassy in Libya at the time, expressed his frustration in an emotionally charged congressional hearing that a U.S. military jet and special forces were not sent to help in Benghazi.
A report by ABC News provided additional momentum to the highly partisan flap over whether the administration tried to avoid casting the attack as terrorism at a time when the presidential election was less than two months away.
ABC released 12 versions of the administration's "talking points" on Benghazi that appeared to show how various agencies — particularly the State Department and the CIA — shaped what became the Obama administration's initial playbook for explaining how four Americans, including U.S. Ambassador Christopher Stevens, were killed in the attack.
The report showed the final talking points went through a series of revisions that scrubbed references to previous terror warnings, including one regarding the potential threat from al Qaeda in Benghazi and eastern Libya.
"I would call it a cover-up in the extent that there was willful removal of information," Senator John McCain, an Arizona Republican, said on ABC's "This Week".
McCain called for a select congressional committee with a mandate to interview "everybody," including former Secretary of State Hillary Clinton, who has already testified before Congress on the matter and accepted responsibility for the tragedy.
But McCain's call was brushed off by fellow Republican Representative Darrell Issa, who chairs the House of Representatives Oversight and Government committee that heard from Hicks last week.
"You know, let's not blow things out of proportion. This is a failure, it needs to be investigated. Our committee can investigate," Issa said.
Issa said he would be sending a request on Monday to privately depose two former U.S. officials that headed the Accountability Review Board, which investigated the Benghazi attacks and issued a scathing report on December 18 that criticized security at the mission and leadership "deficiencies".
Issa said he wanted to hear from Thomas Pickering, a former U.S. ambassador in the Middle East, Russia and India, and retired Admiral Michael Mullen, former Chairman of the Joint Chiefs of Staff, privately "so we can get the facts in a nonpartisan way."
Senator Jack Reed, a Rhode Island Democrat, told ABC News there was no basis to Republican charges of a cover up.
The Obama administration has provided over 25,000 pieces of documentation to Congress, which has already held 11 hearings on the matter, Reed said.
Meanwhile, Former Defense Secretary Robert Gates, a Republican who served in Obama's Democratic administration, told CBS' "Face the Nation" it would have been "very difficult, if not impossible" to rescue the U.S. embassy officials and said he would have not have approved such an operation.
"To send some small number of special forces or other troops in without knowing what the environment is, without knowing what the threat is, without having any intelligence in terms of what is actually going on the ground, I think would have been very dangerous," Gates said.
"It's sort of a cartoonish impression of military capabilities and military forces" to think the United States could have mounted a rescue, Gates said.
It would have been risky just to send in a military jet to try to scare off the insurgents, "given the number of surface-to-air missiles" on the loose in Libya, he said.