"Birthers" -- those who suspect that Barack Obama was not really born in the United States and is thus Constitutionally barred from serving as President -- have forced themselves into the limelight these past few days. In case you haven't seen it, there's a video making the rounds of GOP US Rep Mike Castle getting heckled on the issue, That video prompted gape-jawed coverage on the blogs and cable news shows (especially MSNBC). And that prompted conservative media titans (Limbaugh, Dobbs, etc.) to engage in serious discussions about why it's actually an important issue.

This is all a perfect example of how the conservative marketplace -- that I wrote about recently -- is driving the right, to the detriment of the Republican Party.

Birtherism is much, much more prevalent than most people realize. It comes up constantly on the right -- it did throughout the campaign, and never really slowed down after. And that's because from a marketing perspective, it sells.

In my conversation with Howard Phillips, head of the Conservative Caucus, I asked him what issues are driving good response rates among organizations on the right (his and others) that raise funds through direct-mail and telemarketing. He said that he expected opposition to Sonya Sotomayor's confirmation to become hot. (This was about two weeks ago, when it didn't seem that way. Indeed, GOP Senator John Thune had complained that Sotomayor opposition “doesn’t have the punch out there in terms of fundraising

and recruiting, I think — at least so far.” Phillips was right; the conservative marketers drummed up the Sotomayor issue, and it became big enough that Republican Senators are now scrambling to try to appease that anger from their base, without looking like total pricks to mainstream America by lining up against a qualified, and dare I say wise, Latina.)

Anyway, Phillips went on to say that conservative organizations that raise money through the mail are honing in on key button-pushing issues like the "death tax," English as the official language, and ratification of the UN Convention on the Law of the Sea. Clearly, three of the most important, pressing issues facing the US at this moment.

He then added that while he personally does not subscribe to the skepticism surrounding Obama's birthplace, that issue is one of the hottest (and most lucrative) topics of all. Alan Keyes, he noted, has been extensively collecting online signatures on petitions on that issue. (Keyes's online-petition site, which has been a terrific source for generating precious mailing-list info on movement conservatives, went down recently, so I did not include it among his vast empire in that recent article.) Phillips also mentioned Jerome Corsi, who included birther speculation in his 2008 book "The Obama Nation," and repeatedly pushes the theory on the birtherism-obsessed (and extremely popular) WorldNetDaily site. Phillips told me that Corsi is hunting a new theory that involves Obama's Kenyan "grandmother" being the actual mother, so stay tuned for that. (Corsi's next book, however, is on a different topic: why Israel must go to war with Iran. It's coming later this summer.)

Movement conservatives are bombarded with birther stuff, constantly, and it shows. It came up repeatedly among conservatives I spoke with at events during the 2008 campaign -- including the Sarah Palin rallies in New Hampshire. Prior to the "Tax Day Tea Parties," one of the Massachusetts organizers put out a list of recommended signs to bring, and the first two suggestion were birther references. And then there's Dan Itse, the New Hampshire state rep whose "state sovereignty" bill I wrote about a few months ago. Itse told me that states had to fight back because the national governmental structures had become corrupted in the interests of those in power. When I asked him why he felt that the federal courts had become corrupted, he replied that it was apparent by the concerted, and seemingly coordinated way that federal courts were refusing to make Obama prove his US birth.

Think of Republicans like Castle, who have to spend their time listening to these movement conservatives, filled with wild, rabid, absolutist ideas. That's who shows up at GOP events; that's who floods their offices with emails, letters, and phone calls; and, increasingly, that's who they need for contributions, volunteering, and votes (particularly in Republican primaries). So they have to put up with it. Fortunately for those Republican officials, this fact of life within the GOP only rarely gets noticed by anyone outside that world -- for example, during the Presidential campaign, when mainstream reporters were amazed to discover that people at the McCain/Palin rallies believed that Obama was a socialist terrorist Arab Muslim.

It's been getting harder and harder to ignore the rabid right, however, as this round of birther media coverage makes evident. And that's a very ominous problem for the GOP as it tries to gear up for 2010 -- when it wants to be running against Obama's economy, not his birth certificate.