Story highlights "In November, I will not vote for Donald Trump or Hillary Clinton," Bush wrote

Bush said Trump has "not demonstrated" the necessary "temperament or strength of character"

Washington (CNN) Jeb Bush said Friday that he will not vote for Donald Trump in November, joining a list of Republican Party luminaries who will not back the party's presumptive nominee.

"In November, I will not vote for Donald Trump or Hillary Clinton, but I will support principled conservatives at the state and federal levels, just as I have done my entire life," the former Florida governor wrote in a statement published on his Twitter and Facebook accounts . "For Republicans, there is no greater priority than ensuring we keep control of both chambers of Congress. I look forward to working hard for great conservatives in the Senate and House in the coming months."

Trump has "not demonstrated" the necessary "temperament or strength of character. He has not displayed a respect for the Constitution. And, he is not a consistent conservative. These are all reasons why I cannot support his candidacy," Bush said.

Trump responded to Bush at an afternoon rally in Omaha, Nebraska, saying, "No, I won't talk about Jeb Bush. I will not say, I will not say that he's 'low energy,'" Trump said, reviving his memorable nickname for the former Florida governor. "I will not say it. I will not say it."

Bush's announcement marks a reversal from Bush's pledge to support the nominee, even if it turned out to be Trump.