Murphy, a member of the Senate Foreign Relations Committee, said Sunday that "it stands to reason" the Russians want Trump reelected, calling him "a gift to Russia."

"Of course, it stands to reason that they want Donald Trump reelected because he has been a gift to Russia,” Murphy said. "He has essentially ceded the Middle East to Russian interests. He has accomplished more in the undermining of NATO than Russia has in the last 20 years. And he continues to effectively deny that they have an ongoing political operation here in the United States that, by and large, is intended to support Donald Trump and his allies."

CNN host Jake Tapper asked Murphy on Sunday about the fact that the Trump administration has gotten NATO members to spend more on defense than previous presidents and that Trump has increased defense spending.

"What we know is that NATO is weaker today than ever before," Murphy responded. "The fact that Donald Trump has questioned whether or not the United States would even come to the defense of a NATO ally in the future is an invitation to Russia to continue to probe at our borders."

Murphy also responded to comments made by O'Brien on Sunday that it's "no surprise" Russian wants to help get Vermont Sen. Bernie Sanders elected president.

Sen. Bernie Sanders. | Drew Angerer/Getty Images

"Well, our national security adviser should stay out of politics. And that is a political statement," Murphy said.

The Washington Post reported Friday that Sanders was briefed by U.S. officials on Russia's attempt to help his campaign as part of an effort to interfere with the Democratic primaries. Sanders condemned Russian interference, telling Russian President Vladimir Putin that if he is elected president, "trust me, you are not going to be interfering in American elections."

Murphy on Sunday said he was worried about "the politicization of intelligence" by the Trump administration.

"The new acting head of intelligence has no background in intel. He is a Trump loyalist," Murphy said, referring to Trump's new acting director of national intelligence, Richard Grenell.

"I think we all worry about this administration controlling massive amounts of intelligence, massive amounts of classified information, and leaking it out to the press when it advantages them," he said.