Washington ? When the Washington investigative machinery gets rolling, it takes a major event to stop it. National security adviser Condoleezza Rice’s defense of the Bush anti-terror effort at Thursday’s hearing before the Sept. 11 commission was not enough.

But while the hotly anticipated hearing — a sometimes testy affair played out before live television cameras — failed to end the scouring of the Bush administration, it helped to narrow the focus to this: What did President Bush and his senior advisers know in the summer of 2001 about a flurry of terrorist threats picked up by intelligence services, and what did they do about it?

That piece of the puzzle remained in dispute in part because of questions about a key classified document that detailed terror threats to Bush about a month before the 9-11 attacks. Commissioners called on the White House to make the document public, which seems certain to keep the investigation in the headlines.

In his blockbuster testimony two weeks ago, former counterterrorism chief Richard Clarke leveled two basic charges. The first has receded: that the Bush administration ignored his plans for disrupting the al-Qaida terror network in early 2001, plans that included possible military action against the Taliban in Afghanistan. Rice and the commissioners spent little time on that indictment because Clarke himself undercut it when he said it would not have prevented 9-11.

Instead, they sparred over Clarke’s second charge — that top officials, including Bush and Rice, were listless in the face of the summertime “threat spike.” Rice insisted that she and the president did all they reasonably could to address “frustratingly vague” threats despite being hobbled by longstanding legal and bureaucratic barriers.

Among Democrats, many felt that Rice’s testimony had pushed the trail of blame directly to President Bush.

“Just one month before terrorists claimed the lives of 3,000 Americans at the World Trade Center and the Pentagon, President Bush was on a thirty-day vacation in Crawford, Texas,” said Rep. Elijah Cummings, D-Md., chairman of the Congressional Black Caucus. “He was informed by his national security team that al-Qaida operatives in the United States had the ability to hijack passenger airplanes.”

Cummings was referring to one of the hot spots of Rice’s testimony: She tangled with commission Democrats over the nature of a highly classified briefing Bush received on Aug. 6, 2001. Ben Veniste characterized the briefing as a dire warning of al-Qaida leader Osama bin Laden’s desire to strike America.

The Aug. 6, 2001, briefing tantalizes many Democrats because it cuts directly to Bush’s own understanding of the al-Qaida threat prior to the attacks.

Judging from news accounts at the time, terrorism was hardly a cloud on the national radar. Reporters covering Bush worried over the heat, the length of the president’s vacation, the controversy over stem cell research, and the differences between Crawford and Kennebunkport.

Bush took questions the following day. “I’m working a lot of issues — national security matters,” he told them. But the one he discussed in detail was not terrorism. Iraqi gunners in the no-fly zone had once again tried to shoot down U.S. jets.