In a wide-ranging interview Friday with CNN Special Correspondent Jamie Gangel, the former Florida governor talked about his campaign beyond New Hampshire, but also said he plans to support the Republican nominee -- even if that's Donald Trump.
"I will support the Republican nominee no matter who he or she is," Bush said when asked about Trump. "I've done it my whole entire life. I've signed a pledge to do it. I'll do it."
Late last year, after Bush began launching an aggressive attack strategy against Trump, the former governor's aides began looking into the possibility of Bush not backing Trump should he become the nominee. Lately, Bush tends to say definitively that Trump won't be the party's pick and avoids answering the hypothetical.
But on Friday, he said he would support the eventual nominee, but stressed he doesn't think Trump would win in the general election.
"I want to win, though. I want the Republican Party's candidate to win. I want a conservative to serve in the White House," Bush said. "I believe I'm best qualified and that's why I'm fighting for this."
That pledge of party loyalty also extends to Rubio, he said, though Bush and his allies continue to train their fire on the first-term senator, whose third place finish in Iowa ignited a new round of momentum for his campaign.
Since Iowa, where Bush placed sixth, Bush has been traveling across New Hampshire, diligently trying to compare Rubio and Sen. Ted Cruz to another first-term senator that ran for president eight years ago: Barack Obama.
Bush said Friday that Rubio is "charismatic" but not a "leader." His campaign released a TV ad that included footage of former Sen. Rick Santorum, who ended his campaign this week and backed Rubio but failed to name an accomplishment of Rubio's in the Senate.
Asked if Bush's attacks against Rubio will hurt the "establishment" lane in the Republican race, as some critics have argued, Bush argued that politics is a contact sport.
"He's attacking me," Bush said. "So does that count, or is this just only a one-way street? Is this the child of privilege that has a free pass, whenever everybody else has to fight for it? This isn't bean bag, you know. This is politics. Every campaign, every candidate will be contrasted and compared. Their records needs to be shown."
New Jersey Gov. Chris Christie has also been going after Rubio this week
, raising questions about Rubio's position on abortion. Rubio believes in exceptions to abortion only in cases where the mother's life is threatened, not for rape or incest. He has indicated, though, that as president he would sign legislation banning abortion if it had broader exceptions.
Bush, who considers himself the most pro-life candidate, believes in all three exceptions. Asked if Rubio's position is too extreme, Bush said he "respects" it but thinks it won't resonate with large swaths of voters.
"Politically, it's a tough sell to tell a pro-life mother -- had her daughter been raped -- that she would just have to accept that as a sad fact," he said. "This is not an easy decision, but Marco will have to explain that position."
It's a slight departure from a few months ago when it was reported that the pro-Bush super PAC, Right to Rise USA, was considering plans to attack Rubio on abortion. Asked about it at the time, Bush simply showed signs that he disagreed with the reported strategy.
"I don't think anybody should attack someone who's pro life," Bush told reporters during a stop in Iowa last November
Mostly, Bush is focused on highlighting what he considers Rubio's lack of leadership skills.
"As a speaker of the (Florida) House, he managed a staff of about 40 people," Bush said in the interview Friday. "That's different than running a, you know, state government, where you had 130,000 people that got reduced by 11%."
He denied a New York Times report this week
that said his campaign and that of Christie were secretly coordinating their attacks against Rubio. The two candidates have refrained from attacking each other and have both focused on the freshman senator.
Bush said it wasn't true, but said he was glad he wasn't in a war of words with Christie.
"If he's going after Marco, it means he's not going after me, which warms my heart because I've been on the end of that pole ... by Chris Christie, and he's pretty good at it," Bush said.
With just four days until voters head to the polls in New Hampshire, Bush maintained that he's not feeling any "pressure" and argued that he's optimistic about his changes.
Bush supporter Sen. Lindsey Graham, however, told the New York Times that if Rubio "badly" defeats Bush in New Hampshire, the former governor will be "toast."
Bush brushed off the notion. Asked specifically if getting beat "badly" looks like Rubio placing first or second and Bush coming in fourth or fifth -- a possible scenario according to some recent polls -- Bush flatly said "No."
The candidate pledged to continue on to South Carolina, no matter the results.
"If you want to come visit me from the next week after New Hampshire, I'll be in South Carolina. And the week after that I'll be in Nevada," he said. "We have a national campaign. This is the long haul."