WASHINGTON — Attorneys for convicted former vice presidential aide I. Lewis “Scooter” Libby began working on a request for a new trial yesterday as the Bush White House tried to knock down speculation about a possible pardon in the CIA leak case.

Libby, the former chief of staff to Vice President Cheney, was found guilty of perjury and obstruction in the investigation into the 2003 leak of CIA operative Valerie Plame’s identity. He is the highest-ranking White House official convicted in a government scandal since the Iran-Contra scandal two decades ago.

Government prosecutors led by Patrick Fitzgerald spent nearly four years investigating the case but never charged anyone with the leak. Libby will be the only one charged in the case, Mr. Fitzgerald said.

Libby’s attorneys tried to use that during the trial to persuade jurors that, since nobody was charged in the case, Libby didn’t fear prosecution for the leak and so he had no reason to lie. Juror Denis Collins summed up the dilemma that he and his associates faced behind closed doors.

“There was a frustration that we were trying someone for telling a lie apparently about an event that never became important enough to file charges anywhere else,” he said yesterday on ABC’s “Good Morning America.”

At the White House, President Bush was guarded in his comments.

“This was a lengthy trial on a serious matter, and a jury of his peers convicted him. And we’ve got to respect that conviction,” the president said in an interview with CNN En Español. “On a personal note, I was sad. I was sad for a man who had worked in my administration, and particularly sad for his family.” He said he could not comment further because it was an ongoing legal matter.

The White House press secretary, Tony Snow, brushed off questions about whether Mr. Bush would entertain a pardon for Libby, saying the case remains under legal review. Mr. Snow also said Mr. Cheney’s stature within the administration has not changed or waned as a result of the verdict.