(CNN) - A senior Republican has released names of witnesses for a Wednesday congressional hearing on the deadly attack on the U.S. diplomatic compound in Benghazi, Libya, including two characterized by Republicans as whistleblowers.
Rep. Darrel Issa, the chairman of the House Oversight and Government Reform Committee, praised the State Department officials agreeing to testify.
“They have critical information about what occurred before, during, and after the Benghazi terrorist attacks that differs on key points” from what Obama administration officials have conveyed so far, Issa said in a statement on Saturday.
“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,” Issa said.
The witnesses include Mark Thompson, the acting deputy assistant secretary for counterterrorism; Gregory Hicks, a foreign service officer and former deputy chief of mission/chargé d’affairs in Libya; and Eric Nordstrom, diplomatic security officer and former regional security officer in Libya.
A GOP source said Thompson and Hicks are whistleblowers although Issa did not refer to them as such. Nordstrom has testified previously before Congress about the attack last September 11 that killed Ambassador Christopher Stevens and three other Americans.
Earlier this week, reports surfaced that at least four State Department and CIA employees were being intimidated and blocked from cooperating with Congress in its ongoing examination of Benghazi.
An attorney for one of the State Department officials, who was not identified, said the officials considered themselves whistleblowers and felt threatened with career damage if they appeared before Congress.
President Barack Obama said at a news conference earlier this week that he was unaware of that assertion.
The Obama administration has come under fire from Republicans over questions about inadequate security in Benghazi leading up to the attack as well as its early account that it was a spontaneous act rather than a planned terror attack.
On Tuesday, Republican Sens. Lindsey Graham of South Carolina and John McCain of Arizona reiterated their call for the Senate to establish a special committee to investigate the administration's handling of the attack.
Under federal law, employees identified as "whistleblowers" are protected from repercussions by their employer for giving damaging testimony about a government agency to Congress or an inspector general, an independent investigator within an agency.
CNN’s Elise Labott, Dana Bash and Shirley Henry contributed to this report.