MSNBC's Chris Matthews is under fire after comparing Sen. Bernie Sanders's (I-Vt.) decisive win in the Nevada caucuses to the Nazi invasion of France in 1940, with some on social media calling for the "Hardball" host to resign.

"I was reading last night about the fall of France in the summer of 1940," Matthews said during MSNBC's live coverage of the caucuses on Saturday. "And the general, Reynaud, calls up Churchill and says, 'It's over.' And Churchill says, 'How can that be? You've got the greatest army in Europe. How can it be over?' He said, 'It's over.'"

Criticism quickly poured in on social media over Matthews using the analogy. Sanders is Jewish and most of his family members were killed in the Holocaust.

One such response came from Mike Casca, who serves as Sanders's 2020 communications director.

Sanders easily won the Silver State with 47 percent of the vote with 50 percent of precincts reporting. Former Vice President Joe Biden followed with 19.2 percent, and former South Bend, Ind., Mayor Pete Buttigieg had 15.3 percent.

The Hill has reached out to MSNBC for comment.

--This report was updated on Feb. 24 at 9:52 a.m.