WHEN A PARTY GOES MAD…. There’s plenty of interesting data in the latest Newsweek poll, and I’ve generally focused on what it had to say about President Obama’s standing, the generic congressional ballot, and the economy. Sam Stein highlights a tidbit from the results that I’d overlooked.

A majority of Republicans believe that President Barack Obama “sympathizes with the goals of Islamic fundamentalists who want to impose Islamic law around the world,” according to a survey released on Monday.

That figure, buried at the very end of a newly released Newsweek public opinion poll, reflects the extent to which a shocking bit of smear and misinformation has managed to become nearly commonplace within the GOP tent.

A full 14 percent of Republicans said that it was “definitely true” that Obama sympathized with the fundamentalists and wanted to impose Islamic law across the globe. An additional 38 percent said that it was probably true — bringing the total percentage of believers to 52 percent. Only 33 percent of Republicans said that the “allegation” (as Newsweek put it) was “probably not true.” Seven percent said it was “definitely not true.”

It’s hard to overstate how truly insane this is. This isn’t, by the way, a matter of the public not knowing what “sharia” means — the question read, “Some people have alleged that Barack Obama sympathizes with the goals of Islamic fundamentalists who want to impose Islamic law around the world. From what you know about Obama, what is your opinion of these allegations?”

Adam Serwer makes the case that “Americans don’t have a very good understanding of what Islamic law is.” That’s no doubt true. For that matter, the poll results, if accurate, may very well be an extension of just reflexive partisan hatred — people who hate the president suspect he may sympathize with foreign Islamic fundamentalists, not because it’s true, but because they hate him so much they’re inclined to believe anything. (“Some people have alleged Barack Obama sympathizes with the goals of Lrrr, the Omicronian ruler of Omicron Persei 8, who intends to come to Earth to enslave humanity. From what you know about Obama, what is your opinion of these allegations?”)

But whatever the rationale, it’s hard to get over the fact that Obama Derangement Syndrome has become so pervasive on the right, literally most of the nation’s rank-and-file Republicans appear to have gone stark raving mad.

If/when there’s a GOP majority on the Hill, Republican officials should probably realize now that this party base will simply not tolerate any kind of constructive policymaking with the White House, making the prospects for a functioning political process next year almost laughable.

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Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.