Rep. Darrell Issa (R-Calif.) on Thursday sent a letter to the State Department demanding more information about the talking points the Obama administration used in the wake of last year’s deadly terrorist attack on a U.S. diplomatic post in Benghazi, Libya. 

Issa says emails he obtained through a subpoena indicate that State Department leadership signed off on talking points that said the attack was due to a spontaneous protest, even though they were aware of a potential terrorist threat in the region at the time of the attack.

“One of your e-mails made clear that some of your colleagues at the State Department headquarters shared these concerns [of a potential terrorist attack],” Issa wrote in a letter to former State Department spokeswoman Victoria Nuland, “You wrote that changes to the talking points did not ‘resolve all my issues or those of my building leadership.’”

“Your e-mail makes clear that Department leadership shared concerns with you about the draft talking points,” Issa said.

Issa also accused the State Department of failing to fully respond to subpoenas on the matter.

The State Department has not returned a request for comment.

Former U.N. ambassador Susan Rice appeared on Sunday news shows following the Sept. 11, 2012 attacks, and said intelligence indicated they were a spontaneous reaction to an anti-Islam video circulating on the Internet. The administration later admitted Rice’s claim was wrong and labeled the event an act of terror.

The State Department has since said the agency was concerned that the preliminary talking points went too far in assigning blame for the attack and would have been inconsistent with what the White House had said at that early stage.

Earlier this year, ABC News obtained State Department emails that showed numerous versions of the talking points being negotiated between various agencies, including the CIA.

In one of the emails, Nuland objected to a paragraph in the talking points that referenced specific terrorist threats in the region because it “could be abused by members [of Congress] to beat up the State Department for not paying attention to warnings.”

Issa, the chairman of the House Oversight Committee, has fought to keep the controversy in the headlines. Last week he subpoenaed State Department documents detailing the inner workings of the independent board that probed the September attack.

Issa has primarily focused his investigation on the State Department, although recent reports indicate the CIA had a heavy presence in the area at the time of the attack.

According to a CNN report released last week, “dozens” of CIA operatives were on the ground at the U.S. diplomatic annex in Benghazi during the attack that ended with the deaths of Ambassador Christopher Stevens and three other Americans.

The report says that Langley is taking extreme measures — including conducting monthly polygraph tests — to hide the agency’s operations in Benghazi and northern Libya at the time of the attack.