President Obama's administration knew a militant group claimed responsibility for a terrorist strike at the U.S. consulate in Benghazi, Libya, just two hours after violence broke out there, opening up the White House to a fresh round of scrutiny over its public claims about the deadly attacks.

Officials in the White House Situation Room, among others, were told Islamist group Ansar al-Sharia said on social media that it initiated the Sept. 11 attack that killed four Americans, including U.S. Ambassador Christopher Stevens, new State Department emails reveal.

Top surrogates for Obama on Wednesday were forced to explain why they attributed the violence to an anti-Islam video days after the attacks, as they faced rising speculation that the president misled the public about the incident.

"You know, posting something on Facebook is not in and of itself evidence, and I think it just underscores how fluid the reporting was at the time and continued some time to be," Secretary of State Hillary Clinton said, cautioning reporters not to "cherry-pick one story here or one document there."

White House press secretary Jay Carney also insisted the emails did not undermine Obama's public assertions about the attacks.

"There were emails about all sorts of information that was becoming available in the aftermath of the attack," he said. "The whole point of an intelligence community and what they do is to assess strands of information and make judgments about what happened and who is responsible."

Yet, despite nothing more than vague preliminary findings, the White House attributed the violence to the YouTube video. And Republicans say that Obama, who has spent recent months trumpeting his foreign policy accomplishments, could pay a political price for the slowly emerging details about what actually happened in Benghazi.

On the campaign trail Wednesday, Obama talked about the need for Americans to trust the man they elect as president. "There is no more serious issue on a presidential campaign than trust," Obama said in Davenport, Iowa. "Trust matters."

Romney supporters hope to use the emerging details of the Benghazi attack to counter Obama's portrayal of his administration as trustworthy.

"President Obama has destroyed the good will that would normally be afforded to him in a tragedy like this," Matt Schlapp, former White House political director for President George W. Bush, told The Washington Examiner. "This is a big deal. For whatever reason, the Obama administration decided to override eyewitness explanations of what happened to come up with this cover-up that it was a YouTube video."

According to the newly released emails, a State Department official first reported that "20 armed people fired shots" in Benghazi and that Stevens was inside a compound safe house. The second email said the violence had stopped. A third email then said, "Embassy Tripoli reports [Ansar al-Sharia] claimed responsibility on Facebook and Twitter and has called for an attack on Embassy Tripoli."

Republican presidential candidate Mitt Romney showed little appetite for wading into the Libya dispute during the final presidential debate this week. And campaign officials told The Examiner that the incident would be used as part of a broader indictment of Obama's foreign policy record rather than a focal point of their critique against the president.