What began as scattered reports of the firing of some top federal prosecutors has suddenly erupted into a full-blown scandal with Attorney General Alberto Gonzales on the defensive, scrambling to appease his critics and possibly even to hold onto his job.

As recently as Wednesday, in a column in USA Today, he brushed aside questions about the firings as “an overblown personnel matter.” And he sought to explain the dismissals by saying merely “they lost my confidence.”

But on Thursday afternoon Mr. Gonzales reversed himself, went to the Capitol for a private meeting with the Senate Judiciary Committee, and agreed to let five of his aides involved in the firings testify without subpoena. He also dropped his objection to a pending bill that would withdraw his year-old power to appoint federal prosecutors without Senate confirmation.

Most striking of all was a cryptic remark by Sen. Arlen Specter of Pennsylvania, the ranking Republican on the committee and a frequent critic of the Bush administration. Mr. Specter, stung by the Gonzales column, said, “One day, there will be a new attorney general, maybe sooner than later.” (He later said that he hadn’t meant to suggest that Mr. Gonzales was stepping down.)

The concessions came after a week of hearings in which the fired prosecutors told of Republican pressure to hasten investigation of alleged Democratic wrongdoing and go easy in investigating Republicans. In one case, Daniel G. Bogden, an 11-year Justice Department veteran, tried to learn why he was dismissed as U.S. attorney in Nevada. He said he finally reached a senior department official who told him they were attempting to open a slot and bring someone else in, a return to the old discredited spoils system.

This evident politicization of the Justice Department might never have been known if the Republicans hadn’t lost the leadership of both houses last November. The Democrats’ victory gave them the committee chairmanships and, above all, the power to subpoena testimony.

Sen. Patrick Leahy of Vermont, the new committee chairman, has quoted a recent study by two retired professors who compiled a database showing that, between 2001 and 2006, 79 percent of the elected officials and candidates who faced federal investigation were Democrats and only 18 percent were Republicans. Critics have complained that the study merely compiled news reports and press releases and that it said nothing about the party ratio during the Clinton years. The survey nonetheless adds fuel to the outrage over the tactics of the current Justice Department.

It is up to the Judiciary Committee to continue its inquiry and find out the exact circumstances of each dismissal and whether certain senators and representatives violated congressional ethics rules by their repeated telephone calls to U.S. attorneys asking how sensitive investigations and prosecutions were proceeding.

As Attorney General Gonzales said in his column, “Faith and confidence in our justice system are more important than any one individual.” He was referring to the dismissed prosecutors, but the same truism also applies to their boss.