Last July I told you that I knew David Duke personally. He enrolled at LSU in fall 1968, three years after I joined the faculty and two years after I founded the local ACLU chapter. Several times he sought my help when his First Amendment rights were threatened with abridgment.

This July Duke announced his candidacy for the U.S. Senate seat in Louisiana being vacated by David Vitter. When he announced he said, “I’m overjoyed to see Donald Trump and most Americans embrace most of the issues I’ve championed for years.”

Duke last ran for statewide office in 1991. That election went down in Louisiana history as The Governor’s Race from Hell. He had gotten into the run-off with former governor Edwin Edwards, a thoroughly corrupt politician and the most cynical man I’ve ever met. Weeks before the election, bumper stickers appeared in New Orleans that read, “Vote for the crook. It’s important.” It was. Duke polled 55 percent of the white vote, but Edwards won with 60 percent overall thanks to a high black turnout.

Had I been living in Louisiana then, I would have voted for Edwards. The choice wasn’t between the lesser of two evils. Duke and Edwards weren’t to be measured on the same scale. Fascists are sui generis. They respect no traditions, moral standards or laws. They respect force, and only countervailing force can limit their ambition to impose their will on others.

Twice I’ve voted third party in presidential elections. Once was in 2000; I voted for Ralph Nader. Had I not been living in Texas, which was solidly for George W. Bush, I wouldn’t have done so. The next time was 2012; I voted for Rocky Anderson of the Justice Party. Had I not been living in Oregon, which was solidly for Obama, I wouldn’t have done so then either.

There’s personal satisfaction in voting for a candidate who stands for what I stand for even if s/he hasn’t a snowball’s chance in hell of winning. But it’s a small satisfaction, one I readily forgo if there’s any chance my vote will influence the outcome. Why should I demand that political affairs move unimpeded in the direction I think they should, or believe my judgment unerring?

In 1964 the choice between Johnson and Goldwater seemed unambivalent to me. The victor did give us the two great civil rights laws plus Medicare. But he committed us to a full-scale war in Vietnam, the most immoral policy this nation has pursued in my lifetime.

So I say to those of you who, like me, fervently supported Bernie Sanders: If you think you’ll vote third party, don’t. To contribute in any way to the possibility that a fascist will assume the most powerful office in the world would be unconscionable.

I’m not in the habit of calling people fascists, but Duke has recognized a kindred spirit in Donald Trump. This is a man who touts, not his policies (he ad-libs them), but his personal strength. Who has praised Mussolini, Putin, and Saddam Hussein because they are “strong.” Who boasts that he will reinstate waterboarding and “much worse” forms of torture. Clinton and Trump can’t be measured by the same yardstick. One is civilized, the other barbarous.

Do not believe that voting third party will be high-minded. If Trump wins, it will prove an unforgivable self-indulgence.

Herb Rothschild's column appears in the Tidings every Saturday.