Speaking on the floor of the U.S. Senate on Wednesday, Arizona Sen. Jeff Flake challenged his colleagues to speak out when President Donald Trump goes after the media and spreads falsehoods.

Flake called Trump’s attacks on reporters and news outlets unwarranted.

“‘The enemy of the people,’ was what the president of the United States called the free press in 2017,” Flake said. “It is a testament to the condition of our democracy that our own president uses words infamously spoken by Josef Stalin to describe his enemies.”

Flake raised examples of authoritarian regimes in Syria, Venezuela, the Philippines and Myanmar that now use the phrase “fake news” to discredit the media.

Trump often calls reports he doesn’t like “fake news.”

“Here in America, we do not pay obeisance to the powerful,” Flake said. “In fact, we question the powerful most ardently. To do so is our birthright and a requirement of our citizenship.”

Flake is one of the few Republicans in Congress to break with Trump over his behavior. He urged his colleagues to follow suit.

“We are a mature democracy. It is past time to stop excusing or ignoring, or worse, endorsing these attacks on the truth," he said. "For if we compromise the truth for the sake of our politics, we are lost.”

According to the Associated Press, the White House had no immediate comment.

Arizona’s other senator, Republican John McCain, published an op-ed in the Washington Post that echoed Flake’s arguments.

Trump had previously tweeted he would hand out disparaging awards to news outlets today.

Flake isn’t running for re-election.

One of the Republicans trying to replace him, former state Sen. Kelli Ward, said in a statement that the comparison to Stalin was “appalling” and “an embarrassment” to the state.

“It only serves to exacerbate the very problem he claims to be railing against,” Ward said, before calling on the other candidates to publicly condemn the speech.

Former Maricopa County Sheriff Joe Arpaio, another candidate, gave this statement:

“I’m deeply disappointed in Jeff Flake’s speech today bashing President Trump. I think it was totally inappropriate and does nothing to further the conservative cause. If Flake wants to blast the President, fine. That’s expected from him. But he shouldn’t conduct himself that way from the floor of the US Senate. Maybe Flake should just resign now and see how much media attention he gets when he’s not on the Senate floor.”

Congresswoman Martha McSally sent a statement that read, in part:

“I don’t agree with Senator Flake and comparing our President to Stalin, who murdered 20 million people, is absurd. When President Trump talks about fake news, he’s not only referring to negative coverage on himself which independent studies have confirmed is around 90 percent of all broadcast statements, he’s also referring to general media bias."

The Media Research Center recently released a study with the 90 percent claim; it's been reported mainly in right-wing news outlets. On its website, MRC says it's "sole mission is to expose and neutralize the propaganda arm of the Left: the national news media."

McSally also pointed to a survey reported on by the Washington Post that said only 7 percent of journalists identify as Republican. "You don’t have to be a conspiracy theorist to presume there’s bias there," she said.

EDITOR'S NOTE: This story has been updated to include a statement from Joe Arpaio.