(CNN) — Former Georgia Republican Lt. Gov. Geoff Duncan on Monday said he will vote for President Joe Biden in November, arguing former President Donald Trump “has disqualified himself through his conduct and his character.”

“Unlike Trump, I’ve belonged to the GOP my entire life. This November, I am voting for a decent person I disagree with on policy over a criminal defendant without a moral compass,” Duncan, a CNN contributor, wrote in an opinion piece published in the Atlanta Journal-Constitution.

Duncan told CNN’s Laura Coates Monday night that Trump “is not a Republican” and “doesn’t represent our brand.”

“Donald Trump’s not a Republican. He doesn’t represent our brand. He doesn’t represent our future. He’s a horrible human being at this point, we’re watching that play out hour by hour in the courtroom,” Duncan said. “It’s time to move on. If we’re going to heal as a party and truly get back to doing the things that we should do – and that’s be conservative but not angry or crazy or liars – we should turn the page immediately from Donald Trump.”

In the op-ed titled, “Why I’m voting for Biden and other Republicans should, too,” Duncan outlined why he has decided against backing the GOP nominee. While Duncan admitted Biden’s age is a concern for many and his “progressive policies aren’t to conservatives’ liking,” he wrote he was left with no alternative as he argued a second Trump term would hinder the Republican Party from moving forward.

“The GOP will never rebuild until we move on from the Trump era, leaving conservative (but not angry) Republicans like me no choice but to pull the lever for Biden,” Duncan wrote. “The alternative is another term of Trump, a man who has disqualified himself through his conduct and his character. The headlines are ablaze with his hush-money trial over allegations of improper record-keeping for payments to conceal an affair with an adult-film star.”

Duncan criticized fellow members of his party, including Senate Minority Leader Mitch McConnell and New Hampshire Gov. Chris Sununu, calling it “disappointing to watch an increasing number of Republicans fall in line behind former president Donald Trump.” “This mentality is dead wrong,” he added.

Duncan also slammed Bill Barr, once an attorney general for the former president who has since emerged as one of Trump’s most prominent critics, for recently saying he would vote for the presumptive Republican nominee over Biden in November.

“Ironically, having served as his attorney general until December 2020, Barr saw firsthand Trump’s ability to cause damage. Barr’s declaration that the Justice Department uncovered no evidence of widespread voter fraud that could change the outcome of the 2020 election infuriated his boss and set off a chain of events that ended with Jan. 6,” Duncan wrote.

“Trump has shown us who he is. We should believe him. To think he is going to change at the age of 77 is beyond improbable,” Duncan later added.

Trump’s attempt to overturn the 2020 election in Georgia caused Duncan and other Georgia GOP election officials, including Gov. Brian Kemp and Secretary of State Brad Raffensperger, to push back against Trump’s claims of fraud in the state.

Duncan was president of the Georgia state Senate when Rudy Giuliani and other Trump allies spread conspiracy theories about the 2020 election before Georgia state lawmakers in meetings he said at the time he did not “sanction.”

Last year, he testified in front of the Fulton County grand jury that would later indict Trump and others for their attempts to overturn the election in the state. Trump has pleaded not guilty to all criminal charges he faces.

Duncan told CNN’s Jake Tapper after the 2020 election that Trump attacking Kemp and Raffensperger “disgusts” him and spoke about the threats elected officials in the Peach State have received.

“All of us in this position have got increased security around us and our families and it’s not American, it’s not what democracy is all about but it’s reality right now. So, we are going to continue to do our jobs. Gov. Kemp, Brad Raffensperger and myself all three voted and campaigned for the president but, unfortunately, he didn’t win the state of Georgia but it doesn’t change our job descriptions,” Duncan said.

In 2021, Duncan announced he would not run for reelection in 2022, explaining he would instead focus on reforming the GOP.

“We have to move on as Republicans, we have to, and this is our first step to it. … I think Georgians are going to vote against Donald Trump,” Duncan said on “Laura Coates Live.”

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