Former Sen. Jeff Flake (R-Arizona) urged his fellow Republicans this week to not back President Donald Trump‘s 2020 reelection bid, citing the scandal surrounding his phone call with Ukraine’s leader.

In a Washington Post op-ed published Monday titled ‘Fellow Republicans, there’s still time to save your souls,’ Flake — who retired from the Senate in January following a six-year term — said he believes Trump’s actions regarding Ukraine merit impeachment. However, he also voiced concern that such a move could potentially divide the nation.

“A rough transcript of the telephone call has removed all ambiguity about the president’s intent,” Flake wrote. “He is the maestro of a brand of discord that benefits only him and ravages everything else.”

The Arizona Republican added GOP lawmakers should agree the president does not deserve another term in office, regardless of their stance on impeaching Trump. House Democrats announced last week that they would launch an impeachment inquiry into Trump over his decision to pressure Ukraine’s president to investigate Joe Biden and his son for alleged corruption.

“One year into his presidency, I knew that I could not support his reelection,” Flake wrote about Trump in the op-ed. “Though I had hoped that I could still run for reelection to the Senate in 2018 as someone who would help to provide a check on the president’s worst impulses, it soon became apparent that this was not what Republican primary voters in my state were looking for.”

Flake went on to rebuke Trump for his attacks against the press, his demonization of immigrants and refugees and his general disregard for the rule of law and the system of checks and balances. The former Senator ended his op-ed by calling on Republican lawmakers to not lose sight of American values.

“Our country will have more presidents. But principles, well, we get just one crack at those,” Flake wrote. “For those who want to put America first, it is critically important at this moment in the life of our country that we all, here and now, do just that.”

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Despite his longtime opposition to Trump, Flake famously voted to confirm Justice Brett Kavanaugh to the Supreme Court last fall and drew severe criticism for the move. The Arizona Republican was considered one of three moderate conservatives whose swing vote could determine Kavanaugh’s confirmation.