Sen. Jeff Flake (R-Ariz.), an outspoken critic of President Trump, made a shocking announcement on Tuesday that he will not run for reelection.

Flake who faced a tough primary battle, largely due to his unending fights with Trump and former White House chief strategist Stephen Bannon went on to blast the president and Republicans in a Senate speech, accusing his party of abandoning “core principles” in favor of “anger and resentment.”

In his speech at the Senate floor, Flake said he felt out of step with his party, stressing that: “It is clear at this moment that a traditional conservative who believes in limited government and free markets, who is devoted to free trade, and who is pro-immigration, has a narrower and narrower path to nomination in the Republican party — the party that for so long has defined itself by belief in those things”.

“It is also clear to me for the moment we have given in or given up on those core principles in favor of the more viscerally satisfying anger and resentment,” he said.

In the speech, Flake fiercely slammed Trump for the example he’s setting for America’s children, accusing him of railroading “civility and stability” and accusing Republicans of mistaking “reckless, outrageous and undignified behavior” for authenticity.

“If I have been critical, it not because I relish criticizing the behavior of the president of the United States. If I have been critical, it is because I believe that it is my obligation to do so, as a matter of duty and conscience,” he said.

“The notion that one should stay silent as the norms and values that keep America strong are undermined and as the alliances and agreements that ensure the stability of the entire world are routinely threatened by the level of thought that goes into 140 characters — the notion that one should say and do nothing in the face of such mercurial behavior is ahistoric and, I believe, profoundly misguided”, Flake hammered.

The Arizona Senator who never endorsed Trump during the presidential race had earlier enjoyed an outstanding reputation with Republicans on Capitol Hill and a conservative voting record, but saw his popularity plummet with his repeated attacks on Trump.

His antagonistic approach to Trump prompted the president and allies to orchestrate a tough primary challenge to take him down from the right, with former state Sen. Kelli Ward leading the race.