Attorney General Says Alleged Bomb Plot in N.Y. Was 'Very Serious'

In a wide-ranging conversation with Justice Department reporters, Holder said the FBI continues to hunt for those who helped the bomb plot's alleged mastermind, Denver shuttle bus driver Najibullah Zazi, and "it is our intention to bring all who were involved to justice."

"We have a good sense of who these people were, and I can say the investigation is pretty far along and I think we've got a pretty good handle on who was involved," he added.

Holder declined comment on the next phase of the investigation, including the timing on possible arrests. He nonetheless expressed confidence that authorities had defused the alleged al-Qaeda-inspired threat, which may have been intended to kill "scores" of Americans.

Holder used the occasion to call on Congress to swiftly reauthorize provisions of the USA Patriot Act, including tools that allow the FBI to conduct roving wiretaps of suspects, that have helped the bureau and its law enforcement partners in multiple cases. He nodded to the concerns of civil liberties advocates by acknowledging, "There's certainly a conversation that can be had about, do they need to be reexamined," but Holder went on to assert that "the tools as they exist are valuable and not in a theoretical sense."