The back and forth follows a week in which Carville has repeatedly sounded the alarm about a potential Sanders match-up againstin 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.