In the nearly six weeks since his close friend and former chief of staff was convicted of lying and obstructing an investigation, Vice President Dick Cheney has not once spoken to I. Lewis "Scooter" Libby.

Why?

"Well, there hasn't been occasion to do so," Cheney said in an interview broadcast Sunday on CBS' "Face the Nation."

Libby is the highest-ranking White House official convicted in a government scandal since the Iran-Contra affair two decades ago. He was found guilty last month of perjury and obstruction in the investigation into the 2003 leak of CIA operative Valerie Plame's identity.

The episode undercut the Bush administration's credibility, one of a string of a bad-news stories that have hurt the president's standing.

President Bush and Cheney have expressed sadness for Libby and his family, but largely refrained from comment because the matter is an active legal case. Libby plans to appeal.

In the interview, Cheney said he believes deeply in Libby.

"He's one of the most dedicated public servants I've ever worked with, and I think this is a great tragedy," Cheney said.

Yet Cheney has not spoken with Libby to tell him so directly.

Cheney's interviewer, Bob Schieffer, was so surprised to hear that news that he asked the vice president about it again.

Why not calls to express your regrets?

"I just -- I haven't had occasion to do that," was all that Cheney would say.

Libby faces a likely sentencing range of one to three years in prison when he is sentenced June 5.