On his first stop of the day, a town hall at an American Legion Post, he slammed the former secretary of state for pursuing "her own personal ambitions."
"I will take it to Hillary Clinton because I have a proven record," Bush said, adding, "Compare that to the record of personal ambition because that's all she is. It's all about her ... someone who has been organizing her entire life to pursue her own personal ambitions."
He then continued to assail her, as he generally does during these forums, accusing her of changing her position on free trade.
"Hillary Clinton was for free trade before she was against it. Her support, because she's pandering to groups in her own base -- her opposition to this will make it harder for us to be competitive," he said.
This is not the first time, he has made this argument. Back in April, he penned a post on Medium.com, accusing her of a "politically motivated flip-flop," citing the discrepancy between her past support of the Trans-Pacific Partnership, the free trade deal with 12 Pacific Rim countries the Obama administration negotiated, and her current opposition to it.
This barrage of attacks appears well timed. Clinton was just miles from him at the time, preparing for Saturday evening's Democratic debate, hosted by ABC News.
Then, he says he had to get something off his chest.
"Donald Trump is a jerk. You cannot insult your way to the presidency, you can't disparage women, Hispanics, disabled people, who is he kidding? This country is far better than that," he said.
And then he joked.
"I feel better now. I gave myself therapy there," he said. "Thank you for allowing me to do it."