WASHINGTON The State Department now says it never believed the Sept. 11 attack on the U.S. consulate in Benghazi, Libya, was a film protest gone awry, giving congressional Republicans new fodder for criticizing the Obama administration's initial accounts of the assault.

The State Department's extraordinary break with other administration offices came in a department briefing Tuesday, where officials said "others" in the executive branch concluded initially that the protest was based, like others in the Middle East, on a film that ridiculed the Prophet Muhammad.

That was never the department's conclusion, a senior official told reporters.

The Republican-led House Oversight and Government Reform Committee holds a hearing Wednesday on diplomatic security in the attack that killed U.S. Ambassador to Libya Chris Stevens and three other Americans. The attack as become a political football in the final weeks before the election.

The committee's chairman, Rep. Darrell Issa, R-Calif., has accused the State Department of turning aside pleas from its diplomats in Libya to increase security in the months and weeks before the attack in Benghazi. One scheduled witness Wednesday, Eric Nordstrom, is the former chief security officer for U.S. diplomats in Libya who told the committee his pleas for more security were ignored.

• U.S. memo warned of high risk of Libya violence
• Top U.S. counterterrorism adviser in Libya amid questions over security
• Security dwindled before deadly Libyan consulate attack

Briefing reporters Tuesday ahead of the hearing, department officials were asked about the administration's initial -- and since retracted -- explanation linking the violence to protests over an American-made anti-Muslim video circulating on the Internet. One official responded, without specifying, that it was a question for others to answer.

The officials spoke on condition of anonymity because they weren't authorized to speak publicly on the matter, and provided no evidence that might suggest a case of spontaneous violence or angry protests that went too far.

Republican presidential candidate Mitt Romney and Republican lawmakers have increasingly sharpened their criticism of the administration's initial explanation of the attack. They said they never accepted the original explanation.

It was a top administration diplomatic official, United Nations Ambassador Susan Rice, who gave a series of interviews five days after the attack that wrongly described the attack as spontaneous.

She said that the administration believed the violence was unplanned and that extremists with heavier weapons "hijacked" the protest against the anti-Islamic video. She did qualify her remarks to say that was the best information she had at the time. Rice since has denied trying to mislead Congress.

A concurrent CIA memo obtained by The Associated Press cited intelligence suggesting the demonstrations in Benghazi "were spontaneously inspired by the protests at the U.S. Embassy in Cairo" and "evolved into a direct assault" on the diplomatic posts by "extremists."

"A lot of people got the information wrong. Part of the problem is that ... this needs to be an investigation into the facts and what it's come to is a debate on politics in an election year," senior correspondent John Miller said on "CBS This Morning."

Nordstrom, the former security official in Libya, addressed the diplomatic security issue in an Oct. 1 email to a congressional investigator. He said his requests for more security were blocked by a department policy to "normalize operations and reduce security resources."

A memo Tuesday by the Oversight Committee's Democratic staff provided details of Nordstrom's interview with the panel's investigators. In that interview, Nordstrom said he sent two cables to State Department headquarters in March 2012 and July 2012 requesting additional diplomatic security agents for Benghazi, but he received no responses.

He stated that Charlene Lamb, the deputy assistant secretary for international programs, wanted to keep the number of U.S. security personnel in Benghazi artificially low. He said Lamb believed the Benghazi facilities did not need any diplomatic security special agents because there was a residential safe haven to fall back to in an emergency.

Nordstrom's Oct. 1 memo to the congressional investigator said, "You will note that there were a number of incidents that targeted diplomatic missions and underscored the GoL's (government of Libya) inability to secure and protect diplomatic missions.

"This was a significant part of (the diplomatic) post's and my argument for maintaining continued DS (diplomatic security) and DOD (Department of Defense) security assets into Sept/Oct. 2012; the GoL was overwhelmed and could not guarantee our protection.

"Sadly, that point was reaffirmed on Sept. 11, 2012, in Benghazi."

Attached to that memo was a list of 230 security incidents in Libya between June 2011 and July 2012 in a report that ultimately concluded that "the risk of U.S. Mission personnel, private U.S. citizens, or businesspersons encountering an isolating event as a result of militia or political violence is HIGH."

• Read the full memo

New details emerge on Benghazi attack

Senior State Department officials on Tuesday revealed for the first time certain details of the deadly consulate attack, such as the efforts of a quick reaction force that rushed onto the scene and led the evacuation in a fierce gun battle that continued into the streets and included a daring car escape against traffic.

The officials, who spoke to reporters on condition of anonymity because they weren't authorized to speak publicly on the matter, said Ambassador Chris Stevens arrived in Benghazi and held meetings on and off the consulate grounds on Sept. 10. He spent the night, and then out of prudence spent the whole of the 11th anniversary of the 9/11 attacks meeting people inside the compound, an enclosed area about 300 yards long by 100 yards wide, with a 9-foot outer wall topped by barbed wire and augmented by barriers, steel drop bars and other security upgrades.

When Stevens finished his final meeting of the day, he escorted a Turkish diplomat outside the main entrance of the building. The situation was calm, the officials said, and there were no protests. Five U.S. agents and four local militiamen were providing security.

A little more than an hour later, around 9:40 p.m., everything changed.

The compound's agents were alerted by loud noises, gunfire and explosions near the front gate. A barracks near the entrance for the local militiamen was burned down. In the control center, agents watched on cameras as a large group of armed men flowed into the compound. They immediately sounded the alarm and made telephone calls to the embassy in Tripoli, officials in Washington, the Libyan authorities and the U.S. quick reaction force located at a second compound a little over a mile away.

One agent, armed with a sidearm and an assault rifle, took Stevens and State Department computer specialist Sean Smith to a safe room inside one of the compound's two main residences -- an area protected by a heavy metal grill and several locks and stocked with medical supplies and water. The other agents rushed to equip themselves with long guns, body armor, helmets and ammunition at other buildings. Two tried to make it to the building with Stevens but took fire and were forced to retreat.

The attackers began to overrun the compound, the officials recounted. The intruders penetrated Stevens' building and tried to break the grill locks for the safe room but couldn't gain access. So they dumped cans of diesel fuel in the building, lit furniture on fire and set aflame part of the exterior of the building.

In the compound's other residence, two agents barricaded themselves against the attackers who had gotten inside the building. The attackers failed to enter the tactical operations center, where the last two agents were located, smashing the door but failing to break it.

Meanwhile, Stevens' building rapidly filled with thick diesel smoke and fumes from the burning furniture. Inside, visibility was less than 3 feet and, unable to breathe, the Americans went to a bathroom and opened a window, trying to get air. They decided to get out of the building. The security agent went first, flopping out onto a patio enclosed by sandbags and taking fire immediately.

Stevens and Smith didn't make it out, the officials said. The agent, suffering severely from smoke inhalation, went in and out of the building several times to look for them -- in vain. He then climbed a ladder to the roof of the building and collapsed, radioing the other agents in a barely audible voice to alert them to the situation there.

The other four agents were able to then reunite, taking an armored vehicle to Stevens' building. They reached the collapsed agent and tried to set up a perimeter, taking turns going into the building and searching on hands and knees for the missing Americans. Smith was pulled out, dead. Stevens could not be found.

A six-member quick reaction security team arrived on the scene from its compound across town, the officials said. About 60 Libyan militiamen accompanied the team, and it again tried to secure a perimeter around Stevens' building, taking turns searching inside. Taking fire, the Libyan forces determined they couldn't hold the perimeter. An evacuation plan was quickly put in place to retreat to the reaction force's compound.

The evacuation proved anything but easy. Agents piled into an armored vehicle with Smith's body, facing immediate fire as they left through the main gate. Crowds and groups of men blocked two different routes to the security compound, so the Americans looked for an alternate way through heavy traffic at a speed of about 15 mph, so they wouldn't attract attention.

On a narrow street, according to officials, the agents reached a group of men who signaled for them to enter a compound. They sensed an ambush and sped away, but not before taking heavy fire from AK-47 machine guns at a distance of only 2 feet and hand grenades thrown against and under the car. Two tires were blown out.

They raced past another crowd of men and onto a main street, crossing a grassy median into opposing traffic. The agents then drove against oncoming traffic, eventually reaching their compound.

Once there they had to endure several more hours of intermittent gunfire and rocket-propelled grenades fired their way.

A team of reinforcements from the U.S. Embassy in Tripoli arrived on a chartered aircraft at the Benghazi airport and reached the security compound.

But the Americans could do little when their main building was hit by mortar fire around 4 a.m. Two security personnel were killed, and one agent who had been involved in the earlier fighting was severely wounded.

The men decided to leave the city. They spent the next hours securing the annex and moving a large convoy of vehicles to the airport.

They flew out on two planes.