Watching Armstrong during his warmup for Saturday's time trial, the Democrat from Massachusetts listed the Texan's winning qualities.
"What's made him so special at the Tour de France, and as an athlete, is the level of focus, discipline, intelligence, strategic ability, and obviously, his endurance — his ability to just take it on and go," Kerry said.
Those qualities would serve Armstrong well in politics, Kerry said. But Armstrong is also friendly with fellow Texan President Bush.
"I think he'd be awesome, he'd be a force. I just hope it's for the right party," said Kerry, an avid cyclist and longtime fan of the Tour de France.
Kerry said he had tapes of last year's Tour delivered during his presidential campaign last year.
Armstrong, who plans to retire after this year's Tour, sealed a historic seventh straight victory Sunday. He has not ruled out a career in politics after he quits.
Like Armstrong admirers around the world, Kerry wears the yellow rubber "Live Strong" wristband produced by the cyclist's cancer-fighting organization.
"He's a terrific person with an unbelievable personal story, and he understands the seriousness of a number of different choices," Kerry said of Armstrong's comeback from cancer.
"It's one of the great sporting accomplishments of all time," he said. "The sheer willpower is stunning."