10 October 2012 Last updated at 11:24 ET
The Obama administration now describes the incident in Benghazi as a terrorist attack
A former top US security official in Libya wanted more security in Benghazi before a deadly attack on the US consulate, reports say.
Eric Nordstrom received no response to two requests, according to reports ahead of a congressional hearing.
On Tuesday, the state department said it had no "actionable intelligence" on the 11 September attack that killed the US ambassador and three others.
Republicans have criticised the Obama administration over the incident.
According to accounts of an interview by Mr Nordstrom with the House of Representatives committee, he alleged that a state department official, Charlene Lamb, had wanted to keep the security presence in Benghazi "artificially low".
Ms Lamb will also appear before the House Oversight and Government Reform Committee from 12:00 (16:00 GMT) on Wednesday.
She will be joined by state department official Patrick Kennedy and Lt Col Andrew Wood of the US Army, who was in charge of a security support team at the US embassy in Tripoli.
The hearing is part of an investigation into the security situation in Benghazi leading up to the attack.
It is the first public inquiry on Capitol Hill into what went wrong.
Not 'spontaneous'On Tuesday, anonymous state department officials told reporters that the US government had never concluded the sacking of the Benghazi mission was motivated by a US-made video ridiculing Muslims.
They said it was instead a co-ordinated assault involving several groups of men armed with machine guns and rocket-propelled grenades over an expanse of more than a mile.
The 11 September Benghazi assault, in which Ambassador Christopher Stevens and three others died, was unprecedented in recent diplomatic history, officials added.
However, in the days after the attack Mr Obama's ambassador to the United Nations, Susan Rice, initially described it as a "spontaneous" one that arose out of a protest against the film.
The administration says it provided its best intelligence on the attack, and amended that explanation as further information emerged.
The BBC's Kim Ghattas in Washington says the detailed state department briefing appeared to be an effort to preempt criticism the agency is expected to face from the panel.
State department spokeswoman Victoria Nuland said the agency would be "as co-operative as we possibly can" at the hearing on Wednesday.
The agency has launched its own internal review of events.
'Deadly' decisionsAs the 6 November presidential election looms, Republican presidential nominee Mitt Romney has used the Libyan attack to criticise President Barack Obama.
In a speech on Monday, Mr Romney called the Benghazi incident an example of the Democratic president's foreign policy weakness.
A leading Republican on the oversight committee, Representative Jason Chaffetz, told Reuters that he thought the security decisions US officials made for the Benghazi mission had turned out to be "deadly" ones.
Mr Chaffetz said he suspected money and security contractors devoted to Iraq and Afghanistan had drained resources away from US diplomacy security in other parts of the world.
Democrats counter that Republicans are the ones that pushed for cuts in the security that they now deem insufficient.
A memo prepared by the committee's Democratic staff noted that House Republicans voted to reduce funding for embassy security by $459m (£286m) lower that the Obama administration requested.
Democratic staff allege that committee chair Darrell Issa and his staff have failed to consult them, refused to make witness available and withheld documents.
A former top US security official in Libya wanted more security in Benghazi before a deadly attack on the US consulate, reports say.
Eric Nordstrom received no response to two requests, according to reports ahead of a congressional hearing.
On Tuesday, the state department said it had no "actionable intelligence" on the 11 September attack that killed the US ambassador and three others.
Republicans have criticised the Obama administration over the incident.
According to accounts of an interview by Mr Nordstrom with the House of Representatives committee, he alleged that a state department official, Charlene Lamb, had wanted to keep the security presence in Benghazi "artificially low".
Ms Lamb will also appear before the House Oversight and Government Reform Committee from 12:00 (16:00 GMT) on Wednesday.
She will be joined by state department official Patrick Kennedy and Lt Col Andrew Wood of the US Army, who was in charge of a security support team at the US embassy in Tripoli.
The hearing is part of an investigation into the security situation in Benghazi leading up to the attack.
It is the first public inquiry on Capitol Hill into what went wrong.
Not 'spontaneous'On Tuesday, anonymous state department officials told reporters that the US government had never concluded the sacking of the Benghazi mission was motivated by a US-made video ridiculing Muslims.
They said it was instead a co-ordinated assault involving several groups of men armed with machine guns and rocket-propelled grenades over an expanse of more than a mile.
The 11 September Benghazi assault, in which Ambassador Christopher Stevens and three others died, was unprecedented in recent diplomatic history, officials added.
However, in the days after the attack Mr Obama's ambassador to the United Nations, Susan Rice, initially described it as a "spontaneous" one that arose out of a protest against the film.
The administration says it provided its best intelligence on the attack, and amended that explanation as further information emerged.
The BBC's Kim Ghattas in Washington says the detailed state department briefing appeared to be an effort to preempt criticism the agency is expected to face from the panel.
State department spokeswoman Victoria Nuland said the agency would be "as co-operative as we possibly can" at the hearing on Wednesday.
The agency has launched its own internal review of events.
'Deadly' decisionsAs the 6 November presidential election looms, Republican presidential nominee Mitt Romney has used the Libyan attack to criticise President Barack Obama.
In a speech on Monday, Mr Romney called the Benghazi incident an example of the Democratic president's foreign policy weakness.
A leading Republican on the oversight committee, Representative Jason Chaffetz, told Reuters that he thought the security decisions US officials made for the Benghazi mission had turned out to be "deadly" ones.
Mr Chaffetz said he suspected money and security contractors devoted to Iraq and Afghanistan had drained resources away from US diplomacy security in other parts of the world.
Democrats counter that Republicans are the ones that pushed for cuts in the security that they now deem insufficient.
A memo prepared by the committee's Democratic staff noted that House Republicans voted to reduce funding for embassy security by $459m (£286m) lower that the Obama administration requested.
Democratic staff allege that committee chair Darrell Issa and his staff have failed to consult them, refused to make witness available and withheld documents.