But on Sunday, Johnson defended Trump, saying he was "sympathetic with what the president has gone through" and that Democrats were actually relitigating the 2016 presidential election. Other congressional Republicans also eschewed criticism of Trump.

Though he called Johnson "a good friend," Murphy said he's "scared" by Republicans' posture after Trump called on the governments of Ukraine and China to investigate Biden, one of his chief political rivals in the 2020 presidential race.

"That interview was just a giant green light to the president of the United States to continue to solicit foreign interference in U.S. elections," Murphy said of Johnson. "He telegraphed that he's gonna ask China to do the same thing he asked the Ukrainians to do this week because Republicans are allowing to — are — are allowing him to do it."

Still, Murphy predicted public opinion could change rapidly "as you see more Republicans go into the bunker ... and the president go deeper into trying to get ... more countries to interfere in our elections."

"I feel like this is a moment where patriots need to step up and try to save this country," Murphy said. "And I think there are a lot of regular citizens out there that are going to demand that their members of Congress look at the facts, make a decision on the facts, not make a decision based on their loyalty to the cult of Donald Trump."