Republican presidential candidate Jeb Bush this morning said he has “total confidence” that rival Donald Trump will not be the party’s nominee.

“He’s not a serious person and therefore it’s hard to imagine him being president of the United States,” Bush said.

Trump and Ben Carson, another political outsider, have been leading in Iowa, but Bush suggested the way the pair have responded by the terrorist attacks in Paris may be a turning point.

“We have some candidates that are trying to get attention the wrong way,” Bush said. “We’re running for the presidency of the United States. It’s a serious job that requires serious candidates that offer serious plans.”

A recent Quinnipiac University poll found Bush had just five percent support among Republican Caucus-goers. Bush isn’t predicting victory in Iowa, but Bush argued his Iowa organization is the strongest among all the GOP candidates, which will help woo “late deciders”.

“In October and November and even in December of the last two election cycles the people that were winning in December weren’t the individuals that ended up winning,” Bush said. “It’s just the nature of the beast.”

Bush said candidates who appeal to the “fears and angst” among voters won’t win the GOP nomination. And Bush said he won’t be a candidate who tries to “fake people out” with “faux” anger.

“You never win by saying: ‘End is near.’ Name a candidate in national office that said: ‘The end is near. Vote for me,'” Bush said. “At the end of the day, you’ve got to offer a compelling argument to the path we’re on.”

Bush suggested new rules for how primary and caucus results are distributed to candidates may mean the party’s nominee will be chosen by the delegates at the Republican National Convention.

Also today, Bush is strongly disputing a new book’s account of advice Bush got from his brother, George W. — the former president.

“First of all, that book is crap,” Bush said.

The author of “The Wilderness” reports George W. Bush told his brother to say what he needed to say about the Iraq war without concern for the former president’s feelings. Jeb Bush was asked about the book during taping of the Iowa Public Television program, “Iowa Press”.

“Did this not happen, this conversation with your brother?” Catherine Lucey of the Associated Press asked. Bush replied: “There’s no sources…This is the world we’re in now where tabloid journalism is now passing for the kind of journalism that you all have practiced in your careers.”

Bush’s appearance on IPTV’s “Iowa Press” will air Friday evening.