Rodman's backing of Trump represents an about face for the man once described by Trump as being "either drunk or on drugs (delusional)" over claims the hotelier promised he would travel with Rodman to North Korea in 2014.
"I got death threats", Rodman said breaking down in tears.
When asked what he expected when he first visited North Korea, Rodman said he was surprised by how much he liked it.
Rodman described Kim as a "big kid" who wants to see the world and he expressed hope that the two leaders will make progress.
Rodman recalled speaking to then president Barack Obama about these conditions, but "Obama didn't even give me the time". I knew things were doing to change. I was the only one who felt so. I was the only one.
Before an interview with Rodman on "Cuomo Prime Time", Clapper said he had long thought Rodman was an important part of the process.
MORE: Dennis Rodman arrives in Singapore ahead of U.S. He wants to come to America. And I think that Trump will realize that Kim Jong Un is a great guy, inside, and put politics aside. That didn't deter me. They do also seem to have a side project, which uses Rodman to promote peace, love and unity. Today is a great day for everybody, Singapore, Tokyo, China, everybody ... it's a great day. "Why do I feel like I just ran a marathon backwards?" another fan said.
Rodman, who expects Tuesday's summit to be a success, said the outcome would be dependent on the ability of the two leaders to strike up a personal relationship.
His earlier visits to North Korea included a basketball game he organized, an event chronicled in the documentary film "Big Bang in Pyongyang", which featured Rodman singing "Happy Birthday" to Kim, as well as scenes of inebriated and erratic behavior by the basketball Hall of Famer.
But Rodman and his agent did say the five-time National Basketball Association champion was contacted, and thanked, by the White House. "He's trying to protect his people, his honor, and everything that has to do with his country". "We need the doors to be open and start fresh and make this world a better place, baby, that's it". He told reporters he wasn't sure if he would meet Kim in Singapore.