The billionaire received a 61 percent favorability rating in Iowa.
“There’s a lot of partisan stuff going on that’s not fair" to Clinton, Klobuchar said.
Bush said Trump's immigration proposals would be too costly and impractical.
“When people see the benefits of our reforms ... I think our numbers will go up," Walker said.
The Louisiana governor said the last 10 years have shown Americans' resilience.
“I think we have to use drones very, very selectively," he said.
Michael Needham said outsiders are in touch with "conservative populist primary voters.”
“The worst part about this is her arrogance,” Christie said.
"“Donald Trump can say whatever he wants to say about Jeb. But saying that he’s low-energy is wrong...
Fiorina was fired as Hewlett-Packard's chief executive a decade ago.
“They didn’t work in the past,” Walker said of attacks on his record.
Brown said if he were Biden, he would give "very serious consideration" to running.
Discussions also turned to the on-air shooting in Virginia and Hurricane Katrina anniversary.
“That is a legitimate issue for us to look at,” Scott Walker said.
Biden is too much of an insider to challenge Sanders, according to New Gingrich.
“I'm talking about enforcing the laws of this country," Walker said.
"It just seems to be one scandal after another,” he said.
“I know that this is not a sprint — it’s a marathon," Andy Parker said.
“I do not accept the fact that I have been weak on this issue," he said.
"I have let the leadership of the Democrats know," Sanders said.
Discussions also turned to a possible Biden presidential run.
"We need to have start having debates about the issues," he said.
“Any change in birthright citizenship ... will take many, many years,” he said.
"I just think it’s a very complicated problem," Christie said.