Eliza Collins

USA TODAY

Jeb Bush will not be voting for Donald Trump.

The former Florida governor and GOP presidential candidate announced on his Facebook page Friday that he wouldn’t vote for either Trump or Hillary Clinton.

“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.

“The American Presidency is an office that goes beyond just politics. It requires of its occupant great fortitude and humility and the temperament and strong character to deal with the unexpected challenges that will inevitably impact our nation in the next four years. Donald Trump has not demonstrated that 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’s father and brother, former presidents George H.W. Bush and George W. Bush, have also declined to endorse the presumptive nominee.

Jeb Bush was one of the most vocal critics of Trump on the campaign trail. Bush, meanwhile, was one of Trump's most frequent targets for insults. Bush, who at the beginning of the race was presumed to be the frontrunner, struggled to escape the "low-energy" nickname Trump hit him with repeatedly during the campaign.

Trump was asked Thursday on Fox News Channel about Bush 41 and 43 declining to back him.

"Well, I understand that. And I understand why they're not. The war in Iraq was perhaps the worst decision ever made in this country's history. It totally destabilized the Middle East, it was a total disaster. It was made by Bush," Trump said. "I took Jeb Bush on very hard. He was very nasty to me. He spent $15 million, $20 million on negative ads on me. You know, nobody mentions that. They just say I was very nasty to him."

At a rally Friday in Omaha, Nebraska Bush said he was 'not surprised' by the decision of all three Bushes not to support him.

Another former 2016 GOP presidential candidate, South Carolina Sen. Lindsey Graham, also said Friday he would not vote for Trump.