“Have you ever seen a guy sweat like Rubio?” Trump asked. He also derided Carson, who in some Iowa polls is leading Trump, as “super low on energy.” 

“He’s even lower-energy than Bush,” he said. 

Trump also took an indirect shot at Carson for his religion.

“I’m Presbyterian. That’s down the middle of road,” he said. “I mean, Seventh-day Adventist I don’t know about.”

Carson is a Seventh-day Adventist, a Protestant denomination that believes in a literal reading of the Bible.