Ex-CIA Director David Petraeus has agreed to testify before congressional lawmakers about what he learned during his investigation into the attacks on the U.S. consulate in Benghazi, Libya, that left four Americans dead, including Ambassador Chris Stevens.

Petraeus will be talking to senators on the Select Intelligence Committee perhaps as early as Friday, sources told The Washington Examiner.

The date "has not been set," a congressional aide said.

Committee Chairwoman Dianne Feinstein, D-Calif., told reporters on Wednesday that the testimony will be limited to Benghazi and will not delve into the burgeoning scandal that cost Petraeus his career.

The former four-star Army general was forced to step down after just 14 months at the helm of the spy agency when the FBI confronted him about an extramarital affair. The relationship included a possible security breach and leak of classified information.

The affair has become entwined with the Benghazi investigation in part because Petraeus' mistress appeared to divulge information about what led to the bloodshed and has suggested she gained access to classified information.

Petraeus, 60, was involved with his biographer, former Army Reserve Maj. Paula Broadwell, 40, who said in an October speech that the Benghazi attackers were seeking to free a group of prisoners that Americans were secretly holding captive in the consulate.

President Obama, in a news conference Wednesday, played down the possibility of a leak and said he had confidence in an ongoing FBI investigation into the matter.

"I have no evidence at this point from what I've seen that classified information was disclosed that in any way would have had a negative impact on our national security," Obama told reporters.

Republicans on Capitol Hill, meanwhile, say they lack confidence in an administration-based probe of Benghazi or the Petraeus affair.

Sens. John McCain of Arizona, Kelly Ayotte of New Hampshire and Lindsey Graham of South Carolina formally requested that Congress assemble a special committee to investigate what caused the attack and how officials responded. The Obama administration initially claimed the deadly assault was a protest of an anti-Muslim video rather than a planned terrorist mission.

The special committee, Graham said, would also examine whether Petraeus leaked classified information during the course of his affair that could jeopardize national security.

"The bottom line is, this process has to give the public confidence that we know the difference between a human failing, an error in judgement, and a national security breach."

Broadwell is the co-author of "All In: The Education of General David Petraeus."

The Associated Press reported that during a July speech at the Aspen Institute, Broadwell suggested there were few barriers to the information she was seeking.

"I had access to everything. It was my responsibility not to leak it, not to violate my mentor, if you will, I was writing about a very close mentor," Broadwell said.

The Petraeus matter has extended to Gen. John Allen, 58, who is in command of U.S. troops in Afghanistan. Allen exchanged thousands of emails with Jill Kelley, 37, of Tampa, Fla. Kelley, a volunteer social liaison at a military base, triggered the probe that toppled Petraeus when she alerted the FBI that she was receiving threatening emails. The emails turned out to be from Broadwell, and the FBI inquiry exposed the affair.