It’s pretty shocking to see Rep. Mike Castle, a moderate Republican from Delaware, being berated by people who think President Obama isn’t a citizen of this country:

Unfortunately, things are only going to get worse. CNN’s Lou Dobbs recently treated the controversy as a legitimate issue on his radio show (audio), country singer Pat Boone is touting it on Newsmax.com, the Fox News website Fox Nation is promoting it, Liz Cheney is refusing to say it’s false, and — most ominously — Rush Limbaugh is actively endorsing the myth (via Ambinder). And these are just the latest developments in a long series of statements by conservative media commentators and analysts promoting the myth.

As the Washington Independent’s David Weigel and The Atlantic’s Marc Ambinder have pointed out, the potency of this issue with the hardcore conservative base is putting Republicans in a difficult position. Many of them are already giving the myth greater legitimacy. In particular, Rep. Bill Posey’s birther-inspired bill requiring presidential candidates to produce their birth certificate is up to nine GOP co-sponsors in the House and is likely to attract more in the coming weeks.

Unfortunately, growing Republican and conservative support means the birth certificate myth will spread widely among the public, particularly among the conservative base, and probably supplant the related Obama Muslim myth as the #1 misperception about the president. Given how difficult it is to correct misperceptions, this is an ominous development — even well-intentioned debunkings like the one administered by Chris Matthews on Hardball last night are likely to fail.

Most importantly, the attention being paid to this myth — which suggests that the President of the United States is illegitimate — is sadly reminiscent of the way that many conservatives inside and outside of Congress lost their minds during the Clinton administration. Are we headed down that same road again? Is the birth certificate myth the equivalent of the conspiracy theory that Clinton had Vince Foster murdered? (Foster’s suicide took place on July 20, 1993 — almost the same point in Clinton’s administration. Things spiraled out of control soon afterward.) It’s a scary thought.