U.S. Attorney General Alberto Gonzales insisted Thursday he played only a small role in the dismissal of eight federal prosecutors, but the senators hearing his testimony in Washington were quick to question his sincerity.

"We have to evaluate whether you are really being forthright," Senator Arlen Specter told Gonzales, the nation's chief law enforcement officer.

Attorney General Alberto Gonzales testifies before the U.S. Senate judiciary committee in Washington Thursday.
(Associated Press/Susan Walsh)

Specter, a Republican from Pennsylvania, said Gonzales's description was "significantly if not totally at variance with the facts."

Gonzales didn't respond to the accusation.

"I don't want to quarrel with you," he told Specter.

The exchange punctuated a long morning of testimony for Gonzales, who told the Senate committee investigating last winter's firings that they were "justified and should stand."

Democrat critics claim the eight U.S. attorneys were fired for political reasons, because they were involved in corruption cases against Republicans. Some critics have called for Gonzales's resignation.

Gonzales and many Republicans contend the dismissals were all performance-related.

On Thursday, Gonzales did concede that "reasonable people might disagree" with the firings. He admitted the process by which the U.S. attorneys were dismissed was "nowhere near as rigorous or structured as it should have been."

Offering an apology to the eight and their families, he also said he had "never sought to mislead or deceive the Congress or the American people" on the matter.

Democrat senators were equally as skeptical of Gonzales's testimony as their Republican counterparts.   

"Since you apparently knew very little about the performance of the replaced United States attorneys, how can you testify that the judgment ought to stand?" asked Senator Edward Kennedy of Massachusetts.