ECHO CHAMBER CASE STUDY…. Once in a while, we can watch a conservative talking point follow a predictable trajectory. What may start as a strange and obscure claim will soon work its way to more conservative blogs. Soon after, Drudge will pick up on it, which usually leads to Limbaugh. From there, it’s a Fox News story, and then accepted conventional wisdom by the Republican Party.

We saw this clearly in February the bizarre fight over the National Coordinator of Health Information Technology. Around the same time, the infamous (and non-existent) high-speed rail between Disneyland and Las Vegas offered another case study.

Ali Frick reports on the latest theory, which actually managed to make its way into the White House last night.

Earlier this week, China’s Central bank Governor Zhou Xiaochuan suggested the need for a “super-sovereign reserve currency,” a move most passed off as China trying to “flex some muscle.” And yet, within days, Fox News’ Major Garrett was demanding whether President Obama supported a “global currency.”

So how did a story that has effectively no basis in reality — and has nothing to do with a global currency — end up as one of the few questions posed to President Obama last night? It started with a blaring banner on the instigator of conservative and media memes, the Drudge Report.

Within hours, right-wing fanatic Rep. Michele Bachmann (R-MN) was demanding that Treasury Secretary Timothy Geithner and Federal Reserve Chairman Ben Bernanke pledge to never adopt a “global currency.” Soon, Fox News’ resident conspiracy theorist Glenn Beck was ranting that a U.N.-imposed global currency was the first step toward world government.

Last night, Fox News’ Major Garrett raised the profile of this nonsense by asking the president directly whether he supports a move to a “global currency.”

The president responded, “I don’t believe that there’s a need for a global currency.”

Will this put far-right minds at ease? I doubt it. Obama’s response was probably all part of an elaborate ruse, quite possibly involving the U.N. The president just wants us to think he opposes a global currency as part of an effort to lure us into a false sense of security.

Don’t worry, Glenn Beck and Michele Bachmann know what’s really going on.

Steve Benen

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.