"It bothers me that someone comes to hijack that cause," Bush said at an event in Summerville, South Carolina. "Donald Trump's not a conservative, and he's not a steady hand for sure, and he's not a servant. It's all about him and I'm the only guy going after him. I don't feel like, that he's intimidating. He's a bully. Punch him back in the nose."
Earlier in the day, Trump taunted Bush on Twitter over turning in his glasses for contact lenses.
"Jeb Bush just got contact lenses and got rid of the glasses. He wants to look cool, but it's far too late. 1% in Nevada!" Trump tweeted on Wednesday.
Bush was asked about why he made the change in an interview with NBC News' Peter Alexander on Tuesday. He said simply that he'd never worn contact lenses before, and hadn't had a chance to go home and see a doctor to get them -- but he admitted there were some other factors at play.
"I've been trying to do this for like three months," Bush said. "I've started doing TV interviews, remote TV interviews, where I can just stare at a camera, you know, a blind camera."
"People said, 'Wow, you look like twenty years younger.' Wow this, wow that," Bush added.
Bush had previously insisted on keeping his glasses. Asked about them back in October
, the former Florida governor said, "I can't see without glasses. I'm not going to take off my stinkin' glasses."
At the time, he joked, "I think I look pretty damn good."
Trump also swiped at Bush's low polling in Nevada while on Twitter Wednesday, referencing a new CNN/ORC poll
that shows Trump in the lead there with 45% support, compared to Jeb Bush finishing last with 1%.
"Just out Nevada poll shows Jeb Bush at 1%, he should take his dumb mouthpiece, @LindseyGrahamSC, and just go home," Trump tweeted, including Bush supporter and South Carolina Sen. Lindsey Graham in his strike.