Cleland, who has a new memoir out called "Heart of a Patriot: How I Found the Courage to Survive Vietnam, Walter Reed and Karl Rove," told host Sheryl Atkisson that "what happens to you in war continues with you in life."
He said his political career, which included being appointed head of the Veterans Administration by President Carter, "helped carry me through" for a while, allowing him to push aside the trauma from Vietnam. But his bitter loss in the 2002 race, which was engineered in part by Rove, stripped Cleland of that protection and resulted in him returning once again to Walter Reed Army Medical Center, where he had initially gone upon his return from Vietnam.
The loss, he said, "threw me right back in war," prompting "massive anxiety" and feelings of "powerlessness and hopelessness" that brought back the sensation of lying bleeding on the battlefield.
Cleland's defeat was tied in part to an infamous ad that showed the triple amputee right after shots of Osama bin Laden and Saddam Hussein. The spot implied Cleland lacked patriotism, and Sen. John McCain called it "worse than disgraceful."
Cleland said Rove employs a strategy of attacking the military service of veterans when representing candidates, like Chambliss, who themselves didn't serve. (He said Rove had used the same tactic against McCain and Sen. John Kerry.) The practice, he said, "crosses the line."
Military service "should be left alone in a campaign," he said, arguing that it should not be a focus regardless of a whether or not a candidate served.
Cleland was getting off a helicopter when he picked up a live grenade that had been dropped by another soldier. It blew up in his hand, taking his limbs and confining him to a wheelchair for the rest of his life.
Asked about the experience of combat veterans returning from Iraq and Afghanistan, some of whom he got to know upon his return to Walter Reed, Cleland said a feeling that "your war is increasingly meaningless" sometimes "compromises your readjustment."
He said he is opposed to adding troops in Afghanistan "if it's still for counterinsurgency," but suggested he would back a troop increase if the troops would be used to train the Afghan military and police. He also said that the United States' focus should be on al Qaeda, which today is largely located in Pakistan.
Watch the full interview with Cleland above. And click here for the full show which also includes an interview with Transnational Crisis Project President Imran Ahmad Kahn on the road ahead in Pakistan and Afghanistan.
"Washington Unplugged" appears live on CBSNews.com each weekday at 12:30 p.m. ET. Click here to check out previous episodes.