Bush took to his Facebook page to congratulate the presumptive Republican nominee, but opted not to support him and to focus on down-ballot races instead.
"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," Bush wrote. "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."
The former GOP presidential candidate noted several times in the post how Trump has been able to tap into supporter's "anger," arguing the real estate mogul's temperament was one reason not to support him.
"Donald Trump has not demonstrated that temperament or strength of character," Bush wrote. "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 joins a growing list of current and former GOP politicians who have spoken out against Trump's presumptive nominee status. While Bush falls in the #NeverTrump camp, he made it clear he wouldn't vote for Hillary Clinton either if she was the Democratic nominee.
"Hillary Clinton has proven to be an untrustworthy liberal politician who, if elected, would present a third term of the disastrous foreign and economic policy agenda of Barack Obama," Bush wrote.