The candidates are now headed to New Hampshire to stump ahead of that state’s primary next week, and some may be changing their playbooks after last night's results.
Even though he was uncharacteristically gracious in his concession speech Monday night, Trump’s second place finish is being widely interpreted as a blow to his campaign’s message.
"His whole candidacy is that he's a winner, so he's got to win," said Mark Jackson, a lecturer at Iowa State.
For his part, Trump stayed quiet overnight but came back out swinging on Twitter today:
"I think this is the first dent in his armor. It is a dent, certainly it could be harmless to him but he has been crafting this narrative of inevitability almost," said Rachel Caufield, an associate professor of political science at Iowa’s Drake University.
The upset will likely impact the way Trump handles himself moving forward in New Hampshire, where he is leading by a wide margin.
"Trump can no longer run as the front-runner who is above the fray," Andersen said. "He is now squarely in the fray. He has to give his supporters something to vote for."
The Real Winner Was Rubio
"At the end of the day, it’s an expectations game. Nobody expected Marco Rubio to garner 23 percent and to just be behind Donald Trump by one point," Caufield said.
"From a Republican perspective, what we have to keep an eye on now is does Rubio's performance here in Iowa...does it boost him in New Hampshire where he's competing against a wide field of establishment candidates?" she said.
Vying for the Establishment Tag
One of the arguments being made about Rubio’s third-place finish is that he now appears to the party's "establishment" candidate.
"The longer John Kasich, Chris Christie and Jeb Bush hang around, the harder it’s going to be for Rubio to truly rival Cruz and Trump," Andersen said.
Different State, Different Electorate
A strong evangelical presence among Iowa Republicans has been credited as part of the reason why Cruz had such a resounding win in Iowa. But the field is quite different in New Hampshire.
"The fact that he does well with conservative Christians and conservative evangelicals just isn’t going to help him in new Hampshire," said Peter Josephson, the chair of the politics department at St. Anslem’s College in New Hampshire.
"We tend to value fiscal conservativism over social conservativism. We’re the live free or die state. We don’t care very much what people are doing in their homes as long nobody gets hurt," Josephson told ABC News.