Paul Begala, a Democratic strategist and CNN political commentator, was a political consultant for Bill Clinton's presidential campaign in 1992 and was counselor to Clinton in the White House. He was a consultant to Priorities USA Action, which was a pro-Obama super PAC before it was a pro-Hillary Clinton super PAC. The opinions expressed in this commentary are his. View more opinion articles on CNN.

(CNN) Once in a while, a politician becomes so powerful and yet so destructive that he or she does real damage to the branch of government in which she or he serves.

Obviously, Richard Nixon damaged the presidency, Newt Gingrich turned the House of Representatives into a mixed martial arts arena, and Roger Taney forever stained the Supreme Court with the Dred Scott decision. But it takes someone special, someone rare, someone spectacularly Machiavellian and malevolent, to screw up all three branches of government.

Ladies and gentlemen: Mitch McConnell. The soft-spoken Kentuckian has, in just a few short years, done lasting damage to the presidency, the Senate and the Supreme Court: the hat trick of democracy destruction.

To wit:

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The presidency. American intelligence knew Vladimir Putin's henchmen were attacking America, using cyberwarfare tactics to undermine Hillary Clinton's campaign. Yet when the nonpartisan leaders of our intelligence community briefed McConnell, his reply -- American intelligence knew Vladimir Putin's henchmen were attacking America, using cyberwarfare tactics to undermine Hillary Clinton's campaign. Yet when the nonpartisan leaders of our intelligence community briefed McConnell, his reply -- according to a new book by Washington Post reporter Greg Miller -- was purely partisan: "You're trying to screw the Republican nominee." McConnell not only refused to condemn the Russians, Miller writes, he threatened to attack the US intelligence community, labeling its call to defend America an act of partisan politics.

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