03/15/2018 11:57 pm ET

Sen. Jeff Flake (R-Ariz.) took aim at his own party over its unwavering support of President Donald Trump.

“Never has a party abandoned and fled its principles and deeply held beliefs so quickly as my party did in the face of the nativist juggernaut,” Flake said on Thursday in a speech to the National Press Club, according to the Arizona Republic. “We have become strangers to ourselves.”

Flake, who is not seeking re-election, said: 

“If we are going to cloister ourselves in the alternative truth of an erratic leader, if we are going to refuse to live in the world that everyone else lives in and reckon with the daily reality that they face, including the very real anxiety that they feel, then my party might not deserve to lead.”

He called on the Republican Party to act now to “mitigate and repair the damage” caused by Trump. 

“As we are discovering and as we will discover for years to come, there is no damage like the damage a president can do,” he said. 

Flake has previously warned that his party could lose elections over its embrace of the president, and he donated to Sen. Doug Jones (D-Ala.) when he was running against Trump-endorsed Roy Moore, who was accused of sexual abusing minors when he was in his 30s.

He has also said a Republican should challenge Trump for the GOP nomination in 2020. On Thursday, Flake said that, while it’s not in his plans, he hasn’t ruled out doing so himself, the Republic reported.

Trump, for his part, has called Flake “unelectable,” slammed his low approval ratings in Arizona and called him “weak on crime & border.”