Three whistleblowers from the State Department are set to testify Wednesday in hearings for the House Oversight Committee’s investigation into whether the Obama administration engaged in a cover-up in the aftermath of the attack on the U.S. consulate in Benghazi, Libya.

Two of the three State Department officials -- Mark Thompson, acting deputy assistant secretary for counterterrorism, and Gregory Hicks, a 22-year foreign service officer veteran and former deputy chief of mission in Libya --  are expected to testify that the consulate requested a military presence and that consular officials feared for their security but were rebuffed.

Also scheduled to testify is Eric Nordstrom, a diplomatic security officer and former regional security officer for Libya.

The Oversight Committee hearing is officially called “Benghazi: Exposing Failure and Recognizing Courage.”

Some Republicans believe the testimonies of Thompson, Hicks and Nordstrom will reveal that the Obama administration was not forthcoming about what it knew during and after the Sept. 1, 2012, attack in Benghazi, which killed U.S. Ambassador Chris Stevens and three other Americans. They say the Obama administration wanted to downplay the ramifications of the incident for political gain.

“I applaud these individuals for answering our call to testify in front of the [House Oversight] committee,” said U.S. Rep. Darrell Issa, R-Calif., the committee’s chairman.

“They have critical information about what occurred before, during and after the Benghazi terrorist attacks that differs on key points from what administration officials -- including those on the Accountability Review Board -- have portrayed,” he said in a statement, referring to the body established by the Obama administration to investigate the attack. “Our committee has been contacted by numerous other individuals who have direct knowledge of the Benghazi terrorist attack but are not yet prepared to testify. In many cases, their principal reticence of appearing in public is their concern of retaliation at the hands of their respective employers. While we may yet add additional witnesses, this panel will certainly answer some questions and leave us with many new ones.”

Hicks is expected to testify that consular officials were aware that the Benghazi attack was an act of terror and not spurred by spontaneous protests, as Obama administration officials initially said.

“I thought it was a terrorist attack from the get-go. I think everybody in the mission thought it was a terrorist attack from the beginning,” Hicks said in an interview with the House Oversight Committee, according to a transcript obtained by CBS.

Hicks reportedly will also say that U.S. special forces were on their way to Benghazi from Tripoli as the attack was unfolding but were told by U.S. Special Operations Command Africa not to head to the consulate.

“They were told not to board the flight, so they missed it,” Hicks reportedly told congressional investigators.

Thompson, a former Marine, is expected to testify that then-Secretary of State Hillary Clinton wanted to limit the department’s counterterrorism bureau from reporting on and making decisions on how to respond to Benghazi, according to Fox News.

Thompson said the input he gave to the Accountability Review Board was scuttled, and he said he’s received threats for agreeing to testify at Wednesday’s hearings.