Mueller argues that the FBI's broad intelligence-gathering capabilities make it ideal to locate and capture terrorists before they strike. He says the FBI has successfully thwarted nearly 100 planned terrorist incidents since Sept. 11, 2001.
In recent weeks, several leading lawmakers have publicly endorsed the idea of creating a new domestic intelligence agency to take over responsibility for coutnerterrorism from the FBI.
"The bureau is not as broken as people would think," a senior FBI official said recently. "Creating a whole new agency would only make the problems we already have even worse."
But there are tensions within the FBI over its own performance that complicate the question of whether it can handle domestic terrorist threats. In an internal memo, Mueller's deputy, Bruce J. Gebhardt, noted that he was "amazed and astounded and at a loss to understand" the continued resistance to pursuing anti-terrorism cases within various field offices.
Sen. Charles E. Grassley, a frequent critic of the FBI who has defended Mueller's reform efforts, warns that the bureau is running out of time to sort things out.
"The FBI deserves a chance to get its act together," Grassley said. "But their time to move from investigating Bonnie-and-Clyde-type crimes to preventing terrorist activities is getting shorter."