Actually, there is one weapon in the arsenal of thoughtful moderates that can still find its mark, wounding or even killing a candidate's chance of reaching office. And what, you ask, is this silver bullet, this wooden stake?
Satire. Satire has a long, successful history in American politics, from the colonial period right up through today. It is considered so fundamental to political discourse that there is a carve-out in the copyright laws specifically permitting the use of copyrighted materials for satirical purposes. Americans seem to respond to satire in a way they don't respond to simple recitations of fact. The evidence is fresh: surely no radio ads, no newspaper editorials, no televised debates played as significant a role in the deterioration of the 2008 McCain/Palin ticket than Tina Fey's razor's edge satire of the inarticulate yet perky vice presidential hopeful.
Still, there are those on whom satire is completely lost. You know them: they're the ones who express shock and dismay that Stephen Colbert could testify in character before Congress on the issue of immigration. They're the ones who find offense, rather than humor, in poking fun at the foibles of one group or another. They're the ones who are sure this country is going straight to hell in a handbasket, and are dumbfounded that the rest of us don't share their righteous outrage.
These people—the humor-challenged, the extremists, the narrow-minded—are, in fact, so blind to satire that they eventually become self-parodies. Tina Fey has said that she used Sarah Palin's own words to skewer her. Dick Cheney's Voldemort impression, straight out of Evil Overlord central casting, is clearly not an act. And Glen Beck... well, really, is there any figure in America today more self-satirical than Beck? His transparent racism, his manufactured tears, his blatant historical revisionism—surely he can't be serious... can he?
In contrast, consider New York politician Anthony Wiener. Wiener, a personal friend of master satirist Jon Stewart and prime satirical target Bill Clinton, has a well developed sense of humor, and knows how to deploy it in support of his cause. No matter what your politics, it is easy to appreciate Wiener's sharp wit; and when you do, you (consciously or otherwise) become more open to Wiener's argument.
Not everyone gets the joke. The Tea Party is perhaps the largest collection of self-satirical characters the country has ever seen. There is no point of view so off the charts, so wildly inappropriate, that some Teabagger is unwilling to advocate for it. Obama is a socialist? Certainly. Obama is a Kenyan? Sure. Obama is a Nazi? Why, yes, he's exactly like Hitler. As the rest of us look on in increasing dismay, the Teabaggers caricature every extremist position in American politics, and proceed to nominate and, soon, apparently, actually elect politicians who share their paranoid delusions.
Beware, then, the parody-immune, the satire-impermeable. They are destined to become more and more like the caricatures the rest of us find so entertaining—that is, until they turn out to be real.