NBC's Tim Russert deflected criticism of his ethics and credibility as the prosecution rested its case Thursday in the obstruction and perjury trial of former White House aide I. Lewis "Scooter" Libby.

The network journalist got the kind of interrogation he usually gives on his Sunday television show "Meet the Press," as attorneys flashed excerpts of his previous statements on a video monitor and asked him to explain inconsistencies.

Russert, who testified that he never discussed outed CIA operative Valerie Plame with Libby, was the final witness called by Special Prosecutor Patrick Fitzgerald.

A law school graduate, Russert avoided several traps that Libby attorney Theodore Wells laid before him. He seemed uncomfortable at times, however, as Wells asked him to explain why he willingly told an FBI agent about a July 2003 conversation with Libby, then gave a sworn statement saying that he would not testify about that conversation because it was confidential.

"Did you disclose in the affidavit to the court that you had already disclosed the contents of your conversation with Mr. Libby," Wells asked.

"As I've said, sir ... "Russert began.

"It's a yes or no question," Wells interrupted.

"I'd like to answer it to the best of my ability," Russert said.

"This is a very simple question. Either it's in the affidavit or it's not?" Wells asked. "Did you disclose to the court that you had already communicated to the FBI the fact that you had communicated with Mr. Libby?"

"No," Russert said.

Wells wants to cast Russert as someone who cannot be believed, who publicly championed the sanctity of off-the-record conversations but privately revealed that information to investigators. Russert said he viewed the FBI conversation and testimony to prosecutors differently.

Russert's credibility is under fire because he and Libby tell very different stories about a July 2003 phone call that is at the heart of the case. The question of which to believe could be a critical jury room issue.

Both men agree that Libby called Russert to complain about a colleague's news coverage. Libby says at the end of the call, Russert told him "all the reporters know" that Plame, the wife of a prominent war critic, worked for the CIA. Russert testified that part of the conversation never occurred.

"That would be impossible," Russert testified Wednesday. "I didn't know who that person was until several days later."

Libby subsequently repeated the information about Plame to other journalists, always with the caveat that he had heard it from reporters, he has said. Prosecutors say Libby concocted the Russert conversation to shield him from prosecution for revealing classified information from government sources.

Libby's attorneys say Russert knew about Plame from colleagues David Gregory and Andrea Mitchell. Mitchell said in an interview that she and other reporters knew Plame worked for the CIA but she later recanted that statement. Wells had hoped to play clips of Mitchell discussing her statements on the Don Imus morning show on MSNBC.

Fitzgerald successfully argued that the tapes not be played.

"We might as well take 'Wigmore on Evidence' and replace it with 'Imus on Evidence,"' Fitzgerald said, referencing the classic treatise on evidentiary law. "There's no Imus exception to the hearsay rule. This has no business in a federal court."

Wells has questioned Russert about other phone conversations he couldn't remember, inconsistencies between his current account and FBI notes of an agent's original interview with him, and the likelihood that he would've let such a high-ranking official off the phone without fishing for some news.

Suggesting that Russert was eager to see Libby face charges, Wells played a video of Russert discussing the impending indictment with Imus. Russert sounded giddy at times in the discussion, laughing and describing the anticipation as "like Christmas Eve."

Russert said he was eager for the story to unfold like any big event.

"Did you take joy in Mr. Libby's indictment?" Fitzgerald asked during follow-up questioning.

"No, not at all," Russert said. "And I don't take joy in being here."

Libby's attorneys also will try to undercut the credibility of former New York Times reporter Judith Miller, who testified that Libby revealed Plame's identity to her. Defense attorney William Jeffress said he intends to call Miller's former boss, Times managing editor Jill Abramson, to try to refute Miller and question her credibility.