Updated

Attorney General Eric Holder and FBI Director Robert Mueller are facing mounting questions over why they neglected to tell the rest of the Obama administration about the investigation into David Petraeus until Election Day, with one top lawmaker now demanding an explanation.

The FBI apparently was sitting in two inquiries. One involved the extramarital affair uncovered between Petraeus and biographer Paula Broadwell. The other involved "inappropriate communications" between lead commander in Afghanistan Gen. John Allen and Jill Kelley, a woman tied to the Petraeus scandal.

Though the FBI investigation that stumbled onto Petreaus' affair had been underway since as early as June and Holder knew since late summer, the Justice Department did not loop in Director of National Intelligence James Clapper -- who then told the White House -- until last Tuesday.

It's unclear how long the FBI was looking at Allen, but according to the Pentagon that case was not forwarded to them until this past Sunday. President Obama is sure to face questions on the scandal at a Wednesday afternoon press conference.

Rep. Lamar Smith, R-Texas, chairman of the House Judiciary Committee, fired off letters on Tuesday to Holder and Mueller demanding answers about when they knew and why this was kept so secret.

More On This...

"Since the resignation of Central Intelligence Agency (CIA) Director David Petraeus on Friday, Nov 9, it has become clear that the Federal Bureau of Investigation (FBI) began an investigation this summer that uncovered his extramarital affair with a journalist as well as possible breaches of security," he wrote. "However, White House and Congressional officials were reportedly first notified of the investigation and (its) connection to General Petraeus just last week."

Smith said he wants "clarification" on the timeline. Mueller, separately, was on Capitol Hill Wednesday to brief the House Intelligence Committee.

Lawmakers are also openly questioning when Petraeus first knew about the investigation -- and whether it impacted his statements to Congress on Sept. 14 about the Libya terror attack.

Petraeus briefed lawmakers that day that the attack was akin to a flash mob, and some top lawmakers noted to Fox News he seemed "wedded" to the administration's narrative that it was a demonstration spun out of control.

Rep. Peter King, R-N.Y., told Fox News he now questions whether Petraeus' statements -- which were in conflict with an FBI brief and in conflict with available raw intelligence -- were in any way impacted by the knowledge the FBI was investigating his affair with Broadwell.

The White House insisted Tuesday that it was not aware of the Petraeus scandal until last Wednesday, blaming FBI "protocols" for not being informed earlier.

Press Secretary Jay Carney said President Obama was "surprised" when he learned last Thursday that Petraeus had carried on an extramarital affair. While the FBI had at that point already been investigating for months, Carney said "protocols" at the agency apparently kept them from notifying Congress and other agencies in the Executive Branch.

"It is simply a fact that the White House was not aware of the situation regarding General Petraeus until Wednesday and the situation regarding General Allen until Friday," Carney said.

Some lawmakers say Holder should have notified the White House -- and certainly should have notified Congress -- but others have pointed to FBI "protocol" to argue that was not warranted.

According to one source, it is long-standing FBI policy for the FBI not to brief Congress or the White House in the middle of a criminal probe that does not involve a security threat.

Still, the timing of the notification was curious. The Justice Department reportedly told Clapper about the probe on Election Day. Clapper told the White House the following day, and Obama learned the day after that, according to administration officials.

The FBI also apparently did not forward the Allen case until the weekend, leading the Pentagon to disclose the case late Monday.

Carney said Tuesday the president still has "faith" in Allen. Obama "believes he's doing and has done an excellent job" in Afghanistan, he said.

Meanwhile, the new acting director at the CIA, Mike Morell, was on Capitol Hill this week to brief lawmakers. He is expected to brief House Intelligence Committee Chairman Mike Rogers, R-Mich., on Wednesday.

Fox News' Catherine Herridge and Chad Pergram contributed to this report.