It is being reported that a man armed with a knife made it further into the White House than the Secret Service originally disclosed.
Omar Gonzalez - a veteran of the Iraq war - jumped over the building's perimeter fence, before overpowering an officer on the door. He then reportedly ran through the main Entrance Hall, past a female security guard and into the 80-foot-long East Room, where he was eventually tackled.
The 42-year-old is said to have passed a staircase leading to the Obamas' living quarters on his way to the East Room.
Republican congressman Jason Chaffetz says his committee was given the information by whistleblowers.
The account contrasts sharply with that of a Secret Service spokesman shortly after the incident on 19th of September. Spokesman Ed Donovan told The Associated Press that Gonzalez had been arrested just inside the North Portico doors of the White House.
The Secret Service also said that night the man was unarmed, although it emerged the following day he had a knife on him. He also had hundreds of rounds of ammunition in his car.
"I'm worried that over the last several years, security has gotten worse - not better," Mr Chaffetz said. He added that his committee's request for a briefing on the incident from the Secret Service had been denied.
The latest details about the security breach are expected to dominate questioning when Secret Service Director Julia Pierson appears before a House committee today. She has ordered an investigation into the incident and a review of security measures in and around the White House.
It has emerged Gonzalez was on the Secret Service radar as early as July when state troopers arrested him in Virginia. They said he had an illegal sawn-off shotgun and a map of Washington tucked inside a Bible with a circle around the White House and other monuments.
The troopers also seized a stash of other weapons and ammunition found in his car.
Gonzalez was interviewed by the Secret Service but they were unable to hold him and he was released on bail. He was stopped and questioned again on 25 August while walking along the south fence of the White House. He had a hatchet but no firearms, and he was not arrested on that occasion.
