NEW YORK–Six months after leaving Washington, a despondent Al Gore expressed frustration and sadness Monday that Bill Clinton no longer calls or makes an effort to maintain their once-close friendship.

Al Gore waits by the phone for a call that may never come.

According to sources close to the former vice president, despite Gore's open invitation to "call or hang out any time," Clinton has not taken the opportunity to contact him since the duo's January departure from office.

"Just before we left D.C., [Clinton] and I sat down and talked about the eight years we'd gone through together," a sweatpants-clad Gore said. "We talked about the good times and the bad times. At the end, we hugged, and he said that even though he had no idea what the future held for him, there was one thing he did know: that we'd always be close."

"I've called him a bunch of times since then, but I've never heard back from him," said Gore, eating a Chipwich while watching TV on his living-room couch. "I guess he's been too busy traveling the world and attending $10,000-a-plate dinners in his honor."

Since January, Clinton has been extremely busy, making numerous paid speaking engagements overseas and establishing himself as a fixture on the New York high-society party circuit. He has been photographed playing billiards with Elizabeth Hurley, taking his daughter Chelsea to a U2 concert, and, most recently, paying a social call to British Prime Minister Tony Blair.

By contrast, Gore has spent the bulk of his time teaching a course at Columbia University, a non-credit seminar called "Covering National Affairs In The Information Age." According to students, the focus of the seminar has shifted recently, largely consisting of an unshaven Gore holding forth on "the forgotten former vice presidents of American history." At the conclusion of the one-hour seminar, he typically returns to his Columbia University office, where he checks his voice mail for messages before taking a leisurely stroll home, often checking his voice mail at least once more en route.

A depressed Gore finishes off a large container of ice cream while watching C-SPAN.

"I realize he's been busy," Gore said. "But I'm sure he could find a spare minute or two just to touch base and say hi. Or even invite me to some of these soirées he's been attending. We used to go everywhere together."

During his eight years in the White House, Clinton faced numerous scandals and crises, including the bombing of the Chinese Embassy in Belgrade, the war in Kosovo, Whitewater, and the Monica Lewinsky sex scandal. Through it all, Gore stood resolutely by his commander-in-chief.

"I thought that over the course of those eight years, we became more than just president and vice president," Gore said. "But now it's apparent that I was wrong. He was just using me for whatever he needed, and then, when he no longer had any use for me, it was out the window with old Al. He even forgot my birthday. I'm such a fool."

Clinton's reasons for not contacting Gore have been a subject of debate within media circles. George Will has referred to the situation as "a continuation of Clinton's longtime pattern of discarding friends," while Newsweek contributing editor Eleanor Clift defended Clinton as "a towering figure in American history who should be allowed to call or not call whomever he pleases."

"In these matters, it's hard to say what Clinton's intentions are," former Clinton advisor George Stephanopoulos said. "In the past, this is how he has distanced himself from people he no longer wants to be friends with–James Carville, for example. On the other hand, it could just be that he's been temporarily swept up in all the hoopla and celebrations. If that's the case, I'm sure it's only a matter of time before Al receives a call."

Whatever the reason, those close to Gore are concerned about his state in recent days.

"All he does is sit around the house and stare at that phone," wife Tipper Gore said. "All it would take is two minutes out of Bill's time, and Al would be on top of the world again. But I think we all know that's not likely to happen anytime soon. Poor Al."