MSNBC host Chris Matthews slammed the Democratic presidential candidates for not going after Sen. Bernie Sanders, I-Vt., more during Wednesday night's debate, warning Democrats that the senator is "running away with this thing."

"I anticipated last night that the smart move for the Democratic candidates, four or five of them, was to go after Bernie because Bernie is running away with this thing," Matthews told the panel on Thursday. "He's running away with it in California, the other candidates look like they won't even get the threshold of 15 percent. He could get 40 to 50 percent. He could get the first ballot nomination the way he's going, and yet they go after the newbie on the block."

Matthews said a "personal frustration" he had with the candidates was how most of them went after former New York City Mayor Mike Bloomberg, who made his debate debut, instead of Sanders.

MSNBC'S CHRIS MATTHEWS SAYS DEMS 'HAVE A PROBLEM' IN IOWA, COMPARES SANDERS TO 'OLD GUY' WITH SOCIALIST LIT

Earlier this month, the "Hardball" host compared Sanders' candidacy to that of former South Dakota Sen. George McGovern.

"Bernie Sanders is not going to be president of the United States, OK? I look back at the '72 race, I was a young volunteer for the DNC [Democratic National Committee]... I've got to tell you, it feels a lot like it. A lot of giddiness, a lot of excitement, thrill about this guy," Matthews explained.

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"You're saying, a lot like [George] McGovern," MSNBC host Joe Scarborough asked, referencing the failed presidential candidate.

"Well, exactly," Matthews replied, "because he excited the party completely, blew away a really good candidate like [then-Sen. Edmund] Muskie, a very good guy, blew him right out of the water because he had some issues."