Attorney General Alberto Gonzales on Tuesday blamed delays in trying terror detainees at Guantanamo Bay on legal challenges filed by their lawyers.

Those trials may start by this summer, Gonzales told Associated Press reporters and editors. He said rules for the military commission are being sent up to Capitol Hill this week.

"It's not for lack of trying," Gonzales said, when asked about the legal fate of detainees who have been held at the military facility, in some cases for five years. "We are challenged very step of the way."

"We are trying as hard as we can to bring these individuals to justice," he said.

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In the wide-ranging interview that lasted an hour, the attorney general defended a number of Bush administration policies criticized by Democrats and civil libertarians as overstepping legal boundaries, including intelligence gathering and the recent firing of U.S. Attorneys.

Gonzales bristled at the suggestion by Democratic senators that the Justice Department's request for the resignations of several U.S. attorneys were politically motivated or intended to circumvent the Senate confirmation process.