President Bush's spy chief sought to defend Attorney General Alberto Gonzales against charges of lying to Congress in a technically worded statement Tuesday hinging on when the government's terror surveillance program got its name.

Senate Judiciary Committee members have questioned whether Gonzales told the truth when he testified last week that a 2004 confrontation between administration officials was not about the president's secret wiretapping program, dubbed the terrorist surveillance program.

The reason presented for Gonzales' claim: The program wasn't given that name by the administration until 2006, long after his now-famous effort to get then-Attorney General John Ashcroft to endorse it.

"I understand that the phrase 'Terrorist Surveillance Program' was not used prior to 2006 to refer to the activities authorized by the president," Director of National Intelligence Mike McConnell wrote in a letter to Sen. Arlen Specter, R-Pa.

McConnell's letter comes a week after Gonzales insisted to the committee that the hospital confrontation was about some other program he would not name because it was classified. Gonzales repeatedly denied that the internal disagreement was about the "program the president has confirmed."

As McConnell noted, Bush did not disclose the existence of the program until after The New York Times revealed it in December 2005.

After reading the letter, Specter neither accepted McConnell's explanation nor absolved Gonzales of questions about his credibility. Specter said he was waiting for a separate letter from the attorney general.

"If he doesn't have a plausible explanation, then he hasn't leveled with the committee," Specter said on CNN.

Gonzales' testimony last week led four Democrats to call for a special counsel to investigate whether he lied in his sworn testimony. Judiciary Committee Chairman Patrick Leahy, D-Vt., gave Gonzales until the end of this week to make changes to his testimony to clear up discrepancies.

McConnell's letter left the clear impression that, technically, there were no discrepancies on the matter of the hospital visit.

Confirmed only in February as the national intelligence director, McConnell indicated the Justice Department helped define the distinction about the surveillance program.

"The details of the activities changed in certain respects over time and I understand from the Department of Justice these activities rested on different legal bases," McConnell wrote in his one-page letter.