WASHINGTON — The State Department said Tuesday it never concluded that the consulate attack in Libya stemmed from protests over an American-made video ridiculing Islam, raising further questions about why the Obama administration used that explanation for more than a week after assailants killed the U.S. ambassador and three other Americans.

The revelation, ahead of a hotly anticipated congressional hearing Wednesday, came as new documents suggested internal disagreement over appropriate levels of security before the attack, which occurred on the 11th anniversary of the Sept. 11 terror attacks on the U.S.

State Department officials provided their most detailed rundown of how a peaceful day in Benghazi devolved into a sustained attack that involved multiple groups of men armed with weapons such as machine guns, rocket-propelled grenades and mortars over an expanse of more than a mile.

But asked about the administration's initial — and since retracted — explanation linking the violence to protests over an anti-Muslim video circulating on the Internet, one official said, "That was not our conclusion." He called it a question for "others" to answer, without specifying. 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.

The attack has become a major issue in the presidential campaign, featuring prominently in Republican candidate Mitt Romney's latest foreign policy address on Monday. He called it an example of President Obama's weakness in foreign-policy matters, noting: "As the administration has finally conceded, these attacks were the deliberate work of terrorists."

The administration counters that it has provided its best intelligence on the attack, and that it refined its explanation as more information came to light. But five days after the attack, Obama's ambassador to the United Nations, Susan Rice, gave a series of interviews saying the administration believed the violence was unplanned and that extremists with heavier weapons "hijacked" the protest and turned it into an outright attack.

She has since denied trying to mislead Congress, and a CIA memo that was 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."

According to an email obtained Tuesday by The AP, the top State Department security official in Libya told a congressional investigator that he had argued unsuccessfully for more security in the weeks before Ambassador Chris Stevens, a State Department computer specialist and two former Navy SEALs were killed. But department officials instead wanted to "normalize operations and reduce security resources," he wrote.

Eric Nordstrom, who was the regional security officer in Libya, also referenced a State Department document detailing 230 security incidents in Libya between June 2011 and July 2012 that demonstrated the danger there to Americans.

Nordstrom is among the witnesses set to testify Wednesday before the House Oversight and Government Reform Committee. According to the panel's chairman, Rep. Darrell Issa, R-Calif., and the head of a subcommittee, Rep. Jason Chaffetz, R-Utah, the State Department refused repeated requests to provide more security for U.S. diplomats in Libya.

"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," Nordstrom's email stated.

Nordstrom said the incidents demonstrated that security in Libya was fragile and could degrade quickly.

Nordstrom also said diplomats in Libya were told not to request an extension of a 16-member special-operations military team that left in August, according to an official of the oversight panel. The official was not authorized to discuss the matter publicly and thus requested anonymity.

The State Department has said it never received a request to extend the military team beyond August, and added that its members were replaced with a security team that had the same skills.

Democrats on the oversight committee were sharply critical of Issa, the chairman, calling his investigation "extremely partisan."

"The chairman and his staff failed to consult with Democratic members prior to issuing public letters with unverified allegations, concealed witnesses and refused to make one hearing witness available to Democratic staff, withheld documents obtained by the committee during the investigation, and effectively excluded Democratic committee members from joining a poorly planned congressional delegation to Libya," a Democratic memo said.

It said in the previous two years, House Republicans voted to cut the Obama administration's requests for embassy security by some $459 million.

The Democratic memo said Nordstrom told committee investigators that he sent two cables to State Department headquarters in March and July 2012 requesting additional diplomatic security agents for Benghazi, but that 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 and that 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.

Issa had a phone conversation Monday with Secretary of State Hillary Rodham Clinton about the committee's investigation.

The FBI is still investigating. Clinton also has named a State Department review panel to look in to the security arrangements in Libya.