Washington ? The Justice Department is refusing to release hundreds of pages of additional documents related to the firings of eight U.S. attorneys, setting up a fresh clash with Capitol Hill in a controversy that continues to threaten Attorney General Alberto Gonzales’ hold on his position.

The Senate Judiciary Committee, whose investigators have been allowed to view, but not obtain copies of, the records in question, is preparing subpoenas for those papers as well as for all e-mails or documents from the Justice Department and the White House connected to the dismissals of the prosecutors.

The new sparring comes as Senate Democrats postponed a long-planned budgetary appearance by Gonzales that had been scheduled for next week. Sen. Barbara A. Mikulski, D-Md., chairwoman of the Appropriations Committee panel overseeing the Justice Department budget, blamed Gonzales’ “leadership failures” Thursday for the postponement and demanded that the prosecutor controversy be settled before he makes his plea for a budget increase.

Sen. Charles E. Schumer, D-N.Y., reiterated Thursday his call for Gonzales to resign and questioned whether the controversy had made it impossible for the attorney general to handle his day-to-day duties. “He cannot talk about the funding and functioning of the Justice Department until he clears the air on U.S. attorneys,” Schumer said.

“Sen. Leahy can certainly understand why Sen. Mikulski did not want the attorney general to turn an important appropriations hearing on the department’s budget priorities into a trial run for his appearance before the Judiciary Committee,” said Tracy Schmaler, a spokeswoman for Judiciary Committee Chairman Patrick J. Leahy, D-Vt.

The move to call off the budget hearing makes Gonzales’ scheduled April 17 appearance before the judiciary panel even more of a make-or-break moment for Gonzales.

Brian Roehrkasse, a Justice Department spokesman, called Mikulski’s decision “regrettable” and said the attorney general should be able to make his budget pitch for an agency that helps “protect the nation from terrorism and violent crime.”

But trust in Gonzales among Capitol Hill Democrats has evaporated amid revelations from the almost 4,000 pages of documents the Justice Department has released to date, some of which have contradicted statements from the attorney general about the dismissals. Gonzales first told the Judiciary Committee, during a hearing 11 weeks ago, that there was no intent to avoid Senate confirmation for the replacements of the prosecutors.