The most likely scenario for a GOP president is a gradual phasing out of ObamaCare mandates, with help from Congress, to avert the chaos that would result from an immediate and complete repeal of the law, he said.

“You’re steering the ship in a different direction but it’s not going in a 180 degree change,” said Miller, a fellow at the conservative American Enterprise Institute. “No matter who is elected, it’s going to be slower and little bit more incremental.”  

Even so, any Republican president would need to act quickly, he warned. By the time the next president takes office, the law will have been in place for nearly seven years.

“You run out of time. Every year into the future makes it harder to go into a different direction,” Miller said, adding that he hasn’t yet endorsed a candidate.