I caught up with him on a breakfast break at his hometown hangout, Rocky's Coffee Shop in Waipahu, where he squeezed in time to work the room before we ordered. Coming back here reminds Caldwell of his childhood.
"Waipahu boy. Born in Waipahu. Waipahu from the plantation" said Caldwell.
He fondly remembers the plantation days, flipping through a family photo album.
"Here's our backyard in Waipahu. Here's the Banyan tree I used to climb in."
Caldwell grew up, the son of the plantation doctor, just up the road from Rocky's.
"The hospital was just down over there."
He took me on a stroll down memory lane. A church used to be the movie theatre, right across from the nurse's cottages, his backyard.
"Everyone knew I was Dr. Caldwell's kid running around. Some days, they had pictures of me running around in my BVD's."
He misses that community connection.
" We've lost that in Honolulu I think because of cars and roads. Everyone rushing about to work because it's so expensive to live here."
This small town boy sees affordable housing, traffic and crumbling infrastructure as the major growing pains facing Honolulu, the 13th largest municipality in the nation. His answer? To recreate the Waipahus of our youth.
"I want to try to recreate these neighborhoods and I want to do it around rail stations."
Caldwell became a fan of rail as a college student at Tufts University in Boston.
"Went to school taking the T."
He worked in Senator Inouye's office in Washington DC in the 70's, before rail got off the ground.
"I saw how Metro transformed the city."
Caldwell believes Oahu's train will get people to work and home faster, giving them more time with their families and neighbors. Something he doesn't get much of right now. Work keeps him away from his wife of 29 years, Donna Tanouye and their 16-year-old daughter Maya.
"What's the bigger challenge? Raising a teenage daughter in today's world or running a city in this economy? I think sometimes raising a teenage daughter is more difficult."
But, with less than a month left before voters pick Honolulu's next mayor, Caldwell's biggest challenge by far? Getting his name out.