The persistence of the birther conspiracy theory, insisting that Obama was not born in the US, is less surprising than some suggest. It is a perfectly consistent outcome of what I have written about as the "movement conservative marketplace," which exists to fuel, and profit from, the right's fear and loathing of Democrats.
To succeed, that marketplace must identify and exploit reasons for that dread and hatred. If one radio host does it better, that's where listeners in that market will go; same with Fox News hosts and guests, book authors and publishers, Web-site content creators, and advocacy-group fundraisers. Hating Obama, in other words, is a very profitable, highly competitive, multi-billion-dollar business.
They work with what they have. With Bill Clinton, cottage industries were woven out of the slightly mysterious death of Vince Foster, and the tragic conflict with the Branch Davidians in Waco, Texas, among other things. Later, the lies of one obscure hater grew into the mendacious "Swift Boat" movement, and delegates wearing purple Band-Aids at the 2004 Republican National Convention to mock John Kerry's allegedly unearned Purple Heart.
Conspiracies come and go, but the ones that stick are the actionable ones. Clinton's obfuscatory deposition (about his affair with an intern) would hardly have rated a blip among the other charges, except for the argument that, as technically a crime while in office, lying under oath was an impeachable offense. Or to take a current example, all of the right's other complaints about health-care reform have vanished since its passage, replaced by the singular horror they see in the mandate for nearly everyone to purchase health insurance — an issue barely mentioned until it became the basis of the court challenge to rule the law unconstitutional.
Birtherism, which grew from a mish-mash of claims that the seemingly mainstream Obama must be a "Manchurian candidate" hiding his past radicalization and Muslim beliefs, doesn't go away because it holds the promise, to believers, of actually removing him from office. That makes them desperate to believe — which is gold for the conservative marketplace.
Mainstream America, for the most part, will no longer treat these birthers as a legitimate part of the discourse. That's why Trump has tried to pivot away, by shifting focus to another part of the "Manchurian candidate" narrative — equally baseless claims that Obama is covering up an embarrassing, or even corrupt, college record.
Obama didn't let him, or other Republicans like him, get away with it. At the Correspondents' Dinner, from his opening "I Am a Real American" music video on, the president used his strong comic delivery to belittle birtherism.
The effect was to expose the birthers as the kids' table — you can't sit there and be taken seriously. But Republicans who don't sit with them will have real trouble.
For a long time now, Republicans could get away with claiming a seat at both tables. Obama has taken that option away now.
That same divide has now opened up for the claims — far more mainstream in the GOP than birtherism ever was — that Obama is dangerously anti-American.