Stetina was eventually caught and dropped by stage winner Julian Alaphilippe (Etixx-QuickStep), while Morton struggled up the final kilometres and ended up seventh on the day, 35 seconds behind the winner.
As he slumped on the side of the road past the finish line, rehydrating and trying to cool down form the day's effort, Morton said Stetina's decision to attack him rather than work with him likely cost each of them a chance for the stage win and the yellow jersey, which is now Alaphilippe's property.
"I attacked with about 5km to go, just to see what would happen," Morton told Cyclingnews. "Pete Stetina came with me but he didn't really want to ride. He sort of sat on and attacked. I got back on him and he didn't want to ride. He attacked again, which probably ended up costing him the stage. If we had worked together it could have been a different story, you know.
"But that's his loss," Morton said, "and my loss as well."
At the post-race press conference, Stetina (Trek-Segafredo) disagreed, saying that riding aggressively early in the climb was his only chance to win the stage and gain time on the time trial specialists ahead of the stage 6 race against the clock on Friday.
"When he went I felt like that was the right time, and I knew that there was that dip and the one 10-second recovery with 2km to go," he said. "I let him lead into that and then it was just time to go all-in to the line. Unfortunately, it ended up being about 700 metres too short, and I kind of ran out of gas, but I had to race that way to give myself the best chance for the rest of the week."
Stetina now trails Alaphilippe by 19 seconds in the general classification, while Morton is 45 seconds back in seventh.
Despite missing his chance for a stage win and the leader's jersey, Morton was buoyed by the fact that he is riding with the top climbers in the race. The former Garmin-Sharp rider competed at the WorldTour level for three years before experiencing some burn out and choosing to race at the Continental level on Jelly Belly with his brother Angus.
Morton's results last year, his first with Jelly Belly, didn't really reflect the talent that once heralded him as an up-and-coming star in the sport; he won a stage and briefly led the Tour of Utah in 2013 when he was just 21.
But the Morton of old appears to be back this season as he won the notoriously difficult Tour of the Gila earlier this month in New Mexico. Morton said he's actually enjoying racing again, which has improved his attitude toward the on-the-go racing lifestyle.