Washington (CNN)Facing a key test in New Hampshire on Tuesday, Jeb Bush called himself a "joyful warrior" and took some shots at the people standing in his in way in the first-in-the-nation primary: Donald Trump and Marco Rubio.
'Joyful warrior' Bush laces into Trump, Rubio
Bush said Monday that "everyone else runs away from the bully," but that he would keep fighting Trump.
"I'm a joyful warrior," Bush told CNN's Dana Bash. "There is a difference between just sitting back and watching someone try to hijack a party that I believe will allow people to rise up again."
He made his case earlier Monday on Twitter, tweeting "@realDonaldTrump, you aren't just a loser, you are a liar and a whiner. John McCain is a hero. Over and out."
Trump responded to Bush Monday in a call to CNN's Wolf Blitzer.
"He's a stiff. He's not a guy that can be president. He doesn't have what it takes," Trump said on "Wolf." "He's a desperate person. He's a sad and, you know, he's a pathetic person. He doesn't even use his last name in his ads. He's a sad person who has gone absolutely crazy. He's a nervous wreck."
Bush also said Monday that Marco Rubio's debate performance proves he isn't ready for the White House.
"When you repeat something over and over again that's basically a canned phrase. It validates a belief that you're not ready to be president," Bush told Bash.
Chris Christie scored points at Saturday night's debate, hitting Rubio for his repeated line that President Barack Obama "knows exactly what he's doing."
The comment spurred many on Twitter to mock Rubio, and resulted in the creation of a Marco Rubio Glitch account.
But Bush, who once worked closely with Rubio when the two were leaders in the Florida Statehouse, said Rubio's debate performance reiterated standing concerns with his former colleague.
"This started, remember, when he himself struggled about what his accomplishments have been," Bush told CNN. "The accomplishments that his campaign offered up -- supporting a bill that became law where he didn't vote for it, taking credit for the elimination of a risk order inside of Obamacare that he didn't sponsor and the passage of one law with (Sen.) Jeanne Shaheen as a sponsor that I'm sure is a good bill. That's it, that's all you can point to."
Following his surprisingly strong third-place finish in Iowa, Rubio became a clear target for Bush, Christie and Ohio Gov. John Kasich, who are all competing for backing from more moderate Republicans and establishment support. Shortly after Rubio's Iowa performance two former competitors -- Louisiana Gov. Bobby Jindal and former Sen. Rick Santorum -- endorsed him, along with Iowa Sen. Deb Fisher.
But Bush pressed his none-too-subtle criticism that Rubio, who is 44 and a one-term senator, is too green for the White House.
"I've got a story to tell and he doesn't and that's the difference. He kind of validated the weakness of his campaign. Now, having said that, what I feel uncomfortable about is that he's a great guy and he's my friend and I admire him," Bush said. "I think I'm more ready to be President. Part of this is comparing and contrasting. I don't feel good when a friend is getting beaten up. I don't feel good about it at all."