A high-level Republican says he expects more witnesses to step forward with information about last year's deadly attack on a US mission in the Libyan city of Benghazi and how President Barack Obama's administration responded to the unfolding events.
Republican charges that White House covered up details of the September 11, 2012, attack have gathered more steam after Greg Hicks, a former US diplomat, told politicians last week he believed more could have been done to stop the assault by fighters.
"I do think we're going to see more whistle blowers. I certainly know my committee has been contacted," Representative Mike Rogers, chairman of the House Intelligence Committee, said in an interview on Fox News Sunday.
Hicks, the second in command at the US embassy in Libya at the time, expressed his frustration in an emotionally charged congressional hearing that a US military jet and special forces were not sent to help in Benghazi.
A report by ABC News provided additional momentum to the controversy 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 US Ambassador Christopher Stevens, were killed in the attack.
The report showed the final talking points went through a series of revisions that removed 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 wilful removal of information," Senator John McCain, the Arizona Republican, said on ABC's This Week.
McCain called for a select congressional committee with a mandate to interview "everybody", including Hillary Clinton, former secretary of state, who has already testified before Congress on the matter and accepted responsibility for the tragedy.
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 us 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 US officials that headed the Accountability Review Board, which investigated the Benghazi attacks and issued a harsh report on December 18 that criticised security at the mission and leadership "deficiencies".
McCain also singled out Clinton, who he suggested would have been aware of the State Department's emails requesting changes to the talking points.
"I think the secretary of state has played a role in this," McCain said.
"She had to have been in the loop some way, but we don't know for sure."
McCain said Clinton should return to Capitol Hill to testify again, calling for a Congressional select committee to further investigate the issue.