Esquire columnist and frequent MSNBC guest Charles Pierce on Monday assailed Marco Rubio for attacking Barack Obama. Regarding the Republican’s assertion that Obama isn’t incompetent, but is intentionally changing America, Pierce raged, “He's saying Barack Obama is undermining the Constitution. That's an impeachable offense. You just don't say that about a sitting president!”

Keep in mind, this is the same person who compared Dick Cheney to Nazi Hermann Goering and genocidal dictator Pol Pot. Regarding Rubio’s debate performance on Saturday, Pierce complained, “Marco Rubio has been a lightweight his whole political career. I mean, let's go to the rest of what he said there.”

He added, “[Rubio] essentially accused the President of the United States of sedition. That's a serious charge. I guarantee you, he has nothing to back that up.”

A transcript of the exchange, which occurred on All In is below: