Former GOP Sen. Jeff Flake says he will not vote for Trump

Former Sen. Jeff FlakeJeffrey (Jeff) Lane FlakeCNN's Dana Bash: Trump loss in Arizona would be 'John McCain's last laugh' Why it's time for a majority female Cabinet Why Maricopa County will choose the next president MORE (R-Ariz.) said in a new interview that he will not vote for President TrumpDonald John Trump Republican Philadelphia official responsible for vote counting says office getting death threats Biden will call governors, mayors about mask mandate Trump campaign voter fraud hotline flooded with prank calls MORE in November, citing concerns going back before the 2016 campaign.

"I just couldn't support [Trump] long before he started to run. The birtherism thing was just too much for me. And then it piled on," Flake, a frequent critic of the president, told The Washington Post.

Flake also said that a second Trump term could turn younger voters away from the Republican Party, pointing to issues including immigration and the environment.

"So for young people who've grown up around minorities or had a different experience than a lot of us in my generation, they don't harbor, I think, some of the prejudices that people in my generation do," Flake said.

He added that a Trump defeat November would be a "long-term" benefit for the Republican Party and "conservatism as well."

"This won't be the first time I've voted for a Democrat — though not for president. Last time I voted for a third-party candidate," he said. "But I will not vote for Donald Trump."

He also predicted that the GOP would change once Trump is out of the Oval Office.

"The pendulum swings when one party takes it too far," he said. "We'll be ourselves again."

Flake, 57, served in the Senate from 2013 to 2019, and was in the House of Representatives for six terms prior to that. 

As a senator, he criticized Trump on multiple issues, including the president's negative comments about the late Sen. John McCainJohn Sidney McCainCindy, Meghan McCain celebrate Biden win Cindy McCain: 'John would want what's best for our country... Joe Biden' How a tied Senate could lead a divided America MORE (R-Ariz.) in 2015.

Flake was also "shocked" to find out his friend and former House colleague, Mike PenceMichael (Mike) Richard PenceLike it or not, a Trump self-pardon may be coming soon Even if Roe is gone, the abortion conflict is far from over Trump Jr. calls out 2024 GOP hopefuls for 'lack of action' MORE, was nominated as Trump's running mate in 2016, according to Politico.