A leading Senate Democrat asked Attorney General Alberto Gonzales Wednesday to clear up apparent conflicts in testimony from Gonzales and former top Justice Department officials about the firing of federal prosecutors and other matters.

Sen. Patrick Leahy, D-Vt., chairman of the Senate Judiciary Committee, sent written questions to Gonzales so he can prepare for his next appearance before the committee, scheduled for July 24.

The Democratic-controlled Congress has been investigating whether politics played a role in the firing of eight U.S. attorneys. Lawmakers also have been examining the Bush administration's use warrant-free eavesdropping in the war on terror.

Gonzales has appeared in front of congressional committees several times, and told the House and Senate Judiciary committees that he hadn't talked with anyone about the investigation into the prosecutor firings.

But Monica Goodling, the Justice Department's former White House liaison, told the House committee in May that she had an "uncomfortable" conversation with Gonzales where he tried to review his version of the prosecutor firings with her.

"Is Ms. Goodling's testimony accurate, and if so, how do you account for your previous, uncorrected testimony to this committee?" Leahy wrote.

Leahy also plans to probe the differing stories lawmakers have heard about the government's warrantless wiretapping program. The Vermont senator said Gonzales told them in Febuary 2006 that no senior Justice Department officials had any concerns about the electronic surveillance program.

However, former Deputy Attorney General James Comey testified that the Justice Department was against the re-certification of the program in 2004.

Comey also said Gonzales, then-White House counsel, tried to persuade Attorney General John Ashcroft to reverse course and recertify the program. At the time, Ashcroft lay in intensive care, recovering from gall bladder surgery.

Ashcroft refused, as did Comey, who was the top Justice Department official during his boss' illness.

The White House recertified the program unilaterally. Ashcroft, Comey, FBI Director Robert Mueller and their staffs prepared to resign. Bush relented, made changes to the program and the agency eventually signed on.

Leahy said he wants Gonzales to explain fully what happened during that exchange.

Gonzales did not answer between 60 to 100 questions the last time he appeared, Leahy said. "I would like to avoid a repeat of that performance," he said.