In an interview with the Iowa Public Television segment "Iowa Press," which is set to air in full this weekend, the former Florida governor also tweaked Ben Carson for making an analogy that compared Syrian refugees to rabid dogs
Asked what he thinks about the rhetoric from some of his rivals in the presidential race, Bush argued that it shows a lack of seriousness.
"It says that we have some candidates who are trying to get attention the wrong way. We're running for the presidency of the United States. It's a serious job that requires serious candidates that offer serious plans," Bush said.
He added that he found Trump's call to track some Muslims in the country
in the wake of the Paris attacks to be inappropriate (Trump later
modified his comments).
"And I don't think that refugees are dogs. That's ridiculous," Bush continued. "I don't think we should be tracking people unless there is well-founded evidence that people are preparing to attack us."
Bush, who trails far behind Trump in the polls, said he doubts the real estate titan will make any apologies for his controversial statements.
"He's not going to apologize for anything, he's not a serious person. It's hard to imaging him being President of the United States. If he gets upset, is he going to start disparaging our allies?" Bush said. "This lack of seriousness is a serious problem for our country. If a guy, capable as he is as a politician, became president, has no clue what he's doing, that's a dangerous thing."
His comments echo sentiments Bush made earlier
in the week, when he said in an interview that a Trump presidency would be "scary."
Bush conceded Wednesday that he'd pledged to support the Republican nominee, no matter who it is, "but I have total confidence that primary voters are not going to support Donald Trump as the nominee."
Bush was also asked if he agreed with comments that his brother, former President George W. Bush, made after the 9/11 attacks, when he stressed that Islam is a peaceful religion.
"Yeah for a great majority of practitioners, it is a peaceful religion. It's been co-opted by radical terrorists that have turned it into a political ideology," he said. "We're not insulting peace-loving practitioners of the Muslim faith, the Islamic faith, by calling ISIS a group of Islamic terrorists."
The interview capped a three-day swing in Iowa, where Bush is struggling to gain traction as candidates like Trump, Carson and first-term Sens. Marco Rubio and Ted Cruz, have taken off. The latest poll in Iowa showed Trump leading the pack at 25%, with Bush in fifth place at 4%, a little more than two months ahead of the Iowa Republican caucuses.
But Bush maintained his organization is strong in the first four early voting states, and he continued to place his faith in history, arguing that voters tend to make their final decision at the last minute.
"In December of the last two election cycles, the people that were winning in December weren't the ones who ended up winning," he said. "It's just the nature of the beast — no reason to rewrite history. People make up their minds late."
Asked if he was angry enough and able to tap into the frustrations expressed by the Republican electorate, Bush rejected the idea that he has to abandon his pledge to run a "joyful" campaign.
"I don't have to be angry. I have to understand why people are angry," he said. "I believe we're the greatest country on the face of the earth. I'm not going to change who I am just because I have to, I'm not going to be a faux candidate. I'm not going to fake people out. I believe if we fix a few big complex things. This is the most extraordinary time to be alive."