As the Republican base experiments with flavors of the week among the GOP presidential candidates, Jon Stewart is urging these voters to stop being so fickle.

“First you guys wanted Bachmann, then Perry, now Christie…. Have you ever considered the possibility that maybe your candidates aren’t the problem — maybe it’s you? You seem hard to please. You’re unrealistic. […]

“It’s like the Republican base is at war with its own talking points. ‘I want someone who is going to cut taxes and balance the budget; someone who’s a skilled orator but doesn’t talk all fancy; a child of poor immigrants who will build a fence to keep them out of this country; someone who’s strong enough for a man but pH balanced for a woman; someone who will roll up their sleeves but not show their arms.’ […]

“It’s like your ideal candidate is a rare super-heavy element that can only exist in a particular particle accelerator and, even then, for only a fraction of a second before you all remembered how much you hate science. You guys need to take a long hard look in the mirror and not come away thinking, ‘There’s something wrong with this mirror.’”

It’s a very good point. The next question is why the Republican base takes such a superficial approach to candidate evaluation. The answer probably has something to do with the search for non-existent perfection.

GOP voters want someone who’s far to the right on all of the key issues, can generate equal amounts of support from the various party factions, and is perceived as mainstream enough to be electable. Who checks off all the boxes? Probably no one. The Republican base was convinced Rick Perry met the standards, right up until they learned about his background on immigration and the HPV vaccine, realized his antipathy towards Social Security would scare seniors, and noticed that the Texas governor has trouble speaking in complete sentences.

Which then led to questions about a slew of other would-be candidates. They don’t seem interested, but really, it wouldn’t have mattered anyway — they all would have been far less appealing to Republican voters just as soon as the base noticed the candidates’ flaws. As Benjy Sarlin explained very well today, “Like a political Heisenberg Principle, undeclared GOP candidates are only unifying saviors until voters actually stop and look at them.”

There are no perfect Republican presidential candidates. There are barely adequate Republican presidential candidates. The sooner the GOP base accepts this, the less incessant chatter we’ll have to put up with about whether [fill in the blank] might be persuaded to jump into the race.

Postscript: Just as an aside, Jon Stewart’s take on Republican voters was spot on, but watching it, a thought occurred to me. As much as I respect and admire Stewart, and enjoy his work immensely — I haven’t missed an episode in years — I sometimes wonder if his criticisms of President Obama fall victim to the same kind of concerns.

In his segment, Stewart characterized the GOP base’s concerns as, ultimately, contradictory — “someone who’s a skilled orator but doesn’t talk all fancy,” for example. But it often seems as if Stewart himself makes this mistake with Obama — he wants a leader who’ll be bipartisan but stand his ground; a president who’ll try to bring the parties together but fight Republican extremism; someone who’ll talk to Americans like adults but use “humor and zing” when naming policy initiatives.

I often think about the closing remarks Stewart made at the end of the Rally to Restore Sanity, in which he showed traffic merging into a tunnel, making the point that this is how Americans “work together to get things done every damn day.” As Stewart explained, “These millions of cars must somehow find a way to squeeze, one by one, into a mile long 30-foot-wide tunnel carved underneath a might river…. And they do it, concession by concession. You go, then I’ll go. You go, then I’ll go. You go, then I’ll go, ‘Oh my God, is that an NRA sticker on your car? Is that an Obama sticker on your car?’ Well, that’s okay — you go, and then I’ll go.”

Obama often seems to take the same approach to policymaking — accept concessions, accept compromise, work as necessary with other side, so long as we make progress and move forward. And sometimes, it seems as if Obama’s “you’ll go, then I’ll go” approach drives Stewart to the point of disgust.

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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.