WHEN NEWT COMPARES AMERICANS TO NAZIS…. From time to time, far-right voices will complain that MoveOn.org ran ads several years ago comparing the Bush administration to Nazis. The ads don’t exist in reality, but facts aside, conservatives keep pushing the myth precisely because of its perceived power: those who compare Americans, especially America’s elected leadership, to Nazis are necessarily loathsome radicals.

We now know, of course, that those rules no longer apply. Not only do assorted right-wing activists appear at Tea Party events with pictures of President Obama with a Hitler mustache, but disgraced former House Speaker Newt Gingrich has published a book that draws the parallels explicitly.

[Gingrich] is promoting his new book, To Save America, which argues repeatedly that the Obama administration and Democrats in Congress are a “secular-socialist machine” that “represents as great a threat to America as Nazi Germany or the Soviet Union.” Gingrich has repeatedly defended this claim, telling both NBC’s Meredith Vieira and Fox News’ Chris Wallace that he truly believes that the Obama administration is an equivalent “threat” to America as brutal dictators like Adolf Hitler and Joseph Stalin. […] In reaching to make his case, Gingrich repeatedly tries desperately to connect the Obama administration with Nazi Germany.

Remember, MoveOn.org was supposed to be expelled from public life forever for an ad the group didn’t run, but Newt Gingrich is sought out by major media outlets as a credible, sane voice on international affairs, all evidence to the contrary notwithstanding.

In fairness, I’ve been pleasantly surprised by the conservatives who agree that Gingrich has gone too far this time. Joe Scarborough described Gingrich’s latest lunacy as “sick” and “shameful” this week. Former Rep. Susan Molinari (R-N.Y.), who was part of Gingrich’s caucus in the 1990s, called Gingrich’s comparison “just crazy.”

But the disgraced, humiliated former Speaker just keeps defending the comparison, insisting that the president and his allies pose an existential threat to the United States, just like the Nazis and the Soviets.

By any reasonable measure, Gingrich really has turned into an unhinged nut, and an embarrassment to himself. It wasn’t too long ago — say, before January 2009 — that comparing American leaders to Nazis was simply beyond the pale of reasonable discourse. And yet, ol’ Newt has done little else recently.

The remaining question is the same as it always is: will this drive Gingrich from polite society? Or will major media outlets continue to perceive the stark raving mad former Speaker as a legitimate, important observer (or, as David Broder called him, a “visionary”)?

I think we know the answers, which is precisely the problem — there’s nothing prominent Republicans can say or do to be driven from the discourse.