In Iowa, Trump could be closer to Cruz than people think

“I look at Trump, and his ceiling is so much higher than everyone else’s,” says Craig Robinson, a former political director of the Iowa GOP who now runs the Iowa Republican blog. “His campaign has gone out and had people self-identify that they’re interested in him, and they’ve captured that data.”

Robinson’s assessment runs counter to one of the dearest-held assumptions of the political punditocracy. Many commentators believe Trump has a high floor but a low ceiling — that is, his supporters really, really support him and are unlikely to go anywhere else, but he doesn’t have much room to grow, because he already has the loyalty of Republicans who are inclined to like him…

“Ted Cruz is swimming in a pond where the capacity is about 30,000 votes,” says Robinson. “I look at Trump and think that Trump is at that 30,000 mark now, and has the ability to blow past it, if they do a good job of turning their people out.”