Sen. Chris Murphy, D-Conn., said Sunday that the United States is in “one of the most dangerous moments America has ever faced” as he accused President Donald Trump of using the federal government to target his political opponents.

“The president of the United States is now employing the full power of the federal government, the FCC, the Department of Justice, in order to punish, lock up, take down off the air all of his political enemies,” Murphy told ABC News’ “This Week” co-anchor Jonathan Karl.

He continued, “As you know, this is what happens in Iran. This is what happens in Cuba. This is what happens in China, in deeply repressive states in which if you have the courage to stand up and speak truth to power, you are silenced. I mean, there is no more fundamental right in America than the right to protest your government.”

In a February interview on “This Week,” Murphy asserted the U.S. was in the midst of “the most serious constitutional crisis the country has faced, certainly, since Watergate.” He said then that he believed Trump was “attempting to seize control of power and for corrupt purposes.”

On Sunday, he questioned when Republicans would call the president out.

“The question today is, when is enough, enough for Republicans?” Murphy said. “Next week, we need every Republican in the Senate, in the House, not only speaking up, but going to Donald Trump and telling him that they are not going to let him get away with this massive, new contraction of speech. This is a decisive moment for the country. It is a decisive moment for Republicans who have to decide to serve this core, fundamental American value: the freedom of speech.”

Trump has rejected criticisms that his administration is trying to restrict free speech, saying that he is seeking to address to what he calls unfair treatment of him by the press.

Murphy introduced a bill called the “No Political Enemies Act” last week, which he said would create “a specific legal defense for those targeted for political reasons.”

“Doesn’t the First Amendment cover that? Is that — is it necessary to have another piece of legislation?” Karl pressed.

“You have Trump sycophants, not just in charge of the DOJ, but sitting in courthouses all over the country. And so, you have a legal system that is increasingly getting rigged against those who are daring to speak up against the president,” Murphy alleged. “Our legislation just simply makes it easier for you to raise First Amendment defenses in court.”