James Carville fired back at Sen. Bernie Sanders (I-Vt.) for calling him "a political hack," calling the self-described democratic socialist "a communist."

The back and forth follows a week in which Carville has repeatedly sounded the alarm about a potential Sanders match-up against President Trump in November, calling the scenario "the end of days" for the Democratic Party while referring to Sanders supporters as "a cult."

Sanders returned fire on Wednesday night during an interview with CNN's Anderson Cooper, arguing that "political hack" Carville represents the establishment his campaign is running against.

"James, in all due respect, is a political hack," Sanders said. "We are taking on Trump, the Republican establishment, Carville and the Democratic establishment. But at the end of the day, the grassroots movement that we are putting together - of young people, of working people, of people of color - want real change."

Carville, who worked as a campaign strategist for former President Clinton, escalated the feud Thursday on Snapchat with former CNN reporter Peter Hamby.

"Last night on CNN, Bernie Sanders called me a political hack," Carville said. "That's exactly who the f--- I am! I am a political hack! I am not an ideologue. I am not a purist. He thinks it's a pejorative. I kind of like it! At least I'm not a communist."

Trump also recently referred to Sanders as a communist.

"I think he's a communist. I mean, you know, look, I think of communism when I think of Bernie," Trump said in an interview with Fox News host Sean Hannity before the Super Bowl.

Sanders dismissed Trump's comment a week later in an interview with Chris Wallace on "Fox News Sunday."

"Obviously I am not a communist," Sanders said, adding that maybe Trump "doesn't know the difference."