Ashcroft and Deputy Attorney General James Comey took the unusual step of holding a conference call with all 93 U.S. Attorneys last week for a "pep talk" to urge them not to let down their guard in light of a potential terror threat, a senior Justice Department official said on Thursday.

The official, who took part in the call, said Ashcroft and Comey reiterated concerns that top U.S. officials have been voicing since the spring -- that al Qaeda may try to attack the United States in the run up to the November election.

"Given that the intelligence was pegged to an attack between now and the election, the closer we get to the election, obviously the smaller the window gets and the greater our concern gets," said the official.

"We are engaged in a full-court press in every corner of the country to try to detect and disrupt the attack that we're worried about. And this is part of that -- enlisting the U.S. attorneys."

The official said Ashcroft was concerned that some prosecutors and law enforcement officials may have let their guard down because there had been so many terror alerts.

"It was a pep talk," he said. "We're pushing energy into the system."

He said state and local police were also urged to stay alert and be on the lookout for any possible terror suspects.