Washington ? Senators postponed testimony by Attorney General Alberto Gonzales in the aftermath of Monday’s deadly Virginia Tech shootings, delaying his chance to defend contradictions about fired federal prosecutors that have taxed his credibility.

Senate Judiciary Chairman Patrick Leahy said the proceedings, initially set for today, would be inappropriate after the shootings in southwestern Virginia. He delayed Gonzales’ appearance until Thursday.

The Bush administration has pushed for Gonzales to testify as soon as possible, and the long-scheduled hearing is widely viewed as the attorney general’s last chance to quiet a controversy that has prompted calls in both parties for his resignation.

Gonzales has struggled for more than a month to clarify what he described as only a limited involvement in the purge that Democrats believe was politically motivated. A group of conservative activists joined the chorus Monday, urging Gonzales to step down for having “debased honesty as the coin of the realm.”

The White House maintained its support for Gonzales. “I think the attorney general has been perfectly honest,” White House spokeswoman Dana Perino said Monday. And Rep. Chris Cannon, R-Utah, defended Gonzales from the political backlash by noting, “This is a town of jerks.”

Gonzales accepts responsibility for some of the confusion, acknowledging in written testimony “that at times I have been less than precise with my words when discussing the resignations.”

He also ordered the Justice Department to release more than 5,700 pages of e-mails, schedules, memos and other documents to show that the firings were not improper.

Sizable majorities of Americans disapprove of how Gonzales has handled the Justice Department’s firing of eight U.S. attorneys and believe they were chiefly fired for political reasons, an ABC News/Washington Post poll released Monday found. Even among Republicans, only 35 percent approve of Gonzales’ handling of the issue and 53 percent attribute the firings to political reasons.

Even so, people favor Gonzales’ firing by only a slim 45 percent to 39 percent margin. The poll’s margin of error was 3 percentage points.