Charles Schumer, a senator, said: "The president must clarify his role in this whole matter.
"The cloud over the US attorneys, the cloud over the justice department, is getting darker and darker, and only the president can dispel it," he said.
Kyle Sampson had resigned in the scandal, but his boss, Gonzales, who denied any direct involvement in the move, has refused to step down.
"I am here not because I give up. I am here because I've learned from my mistakes, because I accept responsibility and because I'm committed to doing my job," Gonzales said.
"[Evidence suggests that Gonzales] "was carrying out the political wishes of the president in at least some of these firings".
Charles Schumer, US senator
Schumer, however, was not mollified by Sampson's departure saying it only "raises the temperature" and "does not take the heat off the attorney-general".
He said evidence suggested that Gonzales "was carrying out the political wishes of the president in at least some of these firings".
Gonzales earlier admitted that two years ago the White House had explored sacking all 93 federal prosecutors under his supervision, but said he summarily rejected the idea as bad and disruptive.
He said Sampson had taken the lead in those efforts and was in contact with the White House.
Schumer also called for immediate investigations of Harriet Miers and Karl Rove, both White House aides, "so that the air can be cleared".
In a separate development, the White House tried to play down a leading military commander's remarks about homosexuality being "immoral".
Peter Pace, the Joints Chiefs chairman, said that "homosexual acts between two individuals are immoral and that we should not condone immoral acts".
"I do not believe the United States is well served by a policy that says it is OK to be immoral in any way," Pace told a newspaper on Monday.
"I should have focused more on my support of the policy and less on my personal moral views"
US Joint Chiefs chairman
On Tuesday, he clarified that he was not speaking in his official capacity.
"I should have focused more on my support of the policy and less on my personal moral views," he said in a statement.
Dan Bartlett, senior adviser to George Bush, said the US president was a staunch supporter of the "don't ask, don't tell" policy introduced in 1993 which allows gays to serve in the military as long as they keep their sexuality hidden.
He said Bush, who wrapped up a five-nation tour of Latin America in Mexico on Tuesday, has been thoroughly briefed.