Several security officials are expected to testify before Congress on Wednesday, potentially shedding new light on the September attack on the U.S. consulate inBenghazi that left four Americans dead.

BENGHAZI, LIBYA (FILE - SEPTEMBER 12, 2012) (REUTERS) - A U.S. congressional committee is expected on Wednesday (May 7) to hear new information about the attack on the U.S. consulate in Benghazi, Libya last September that left four Americans dead, including U.S. Ambassador Christopher Stevens.

Hicks has been described as a whistleblower and it is anticipated that his testimony will describe a sequence of events that differs from the sequence presented byObama administration officials in the days after the event.

The Benghazi assault was a political embarrassment for U.S. President Barack Obama as he campaigned for re-election. Many conservatives continue to assail the Democratic president over security lapses at the weakly defended Benghazipost, as well as the administration's conflicting accounts of what happened there on September 11, 2012.

Testifying before the Senate Foreign Relations Committee in January, then U.S. Secretary of State Hillary Clinton forcefully defended her handling of the attack and denied any effort to mislead the American people.

"With all due respect, the fact is that we had four dead Americans," Clinton said angrily as she testified before the Senate Foreign Relations Committee in January, an appearance delayed more than a month because of her ill health.

"Was it because of a protest, or was it because of guys out for a walk one night who decided they'd go kill some Americans? What difference, at this point, does it make?" she said, making chopping motions with her hands for emphasis.

The attack threatens to stain Clinton's legacy as secretary of state and could cast a longer shadow should she decide to make a White House run in 2016.