The infamous $400 haircuts that also undercut John Edwards presidential message of reducing poverty started with a tip from the campaign of then-candidate Barack Obama.

Reporters don't like to talk about where they get their stories. But Dome isn't giving away a big secret by revealing that during pitched campaign battle, campaigns will feed bad news about the other guy to reporters.

That's how the nation learned that Edwards, running on a platform of reducing the gap between rich and poor, billed his campaign $400 each for two haircuts.

Politico's Ben Smith wrote a brief item on the haircut which became a big national story and a running joke on late night TV. Smith's brief began with a tip from Obama's campaign, according to a new book by Obama campaign manager David Plouffe. Smith confirms it.

"We did much less of this [opposition research] than other campaigns did," Plouffe writes a bit self-servingly, "but there were times we indulged — it was our researchers who found John Edwards's infamous $400 hair cut expenditures."

It's maddening when people assume political reporting is driven by opposition research when you've actually dug up something yourself, but in this case, I'm in no position to contradict Plouffe's account.

So David Letterman's late unpleasantness has Dome thinking a lot about glass houses.

Letterman, of course, has taken one or two jabs at John Edwards over the years. Famously, the late night king of Top 10s, monkey cams and watermelon drops mussed Edwards expensively coiffed hair.

Once Edwards extra-marital affair hit the news, Letterman has mostly gone easy on Edwards, according to a roundup of Edwards jokes. (Leno appears to really, really enjoy picking at Edwards). Dome has previously noted a couple of cracks.

Over the years, Letterman has picked on Eliot Spitzer, David Vitter, Bill Clinton and Gary Hart, the AP's Frazier Moore notes. 

"Big weekend for Gary Hart," cracked Letterman when the Hart scandal broke: "He was campaigning his brains out."

Moore asked politicians to take a shot at Letterman. None did.

Edwards, of course, should feel free to submit a Letterman joke in the comments section. 

John Edwards may not be at the Democratic National Convention, but that doesn't mean he isn't part of the conversation.

David Letterman had some fun at Edwards' expense last night with his Top 10 Democratic National Convention Pickup Lines. The number one pickup line?

"Hi, I'm John Edwards."

Cue the band.

Illinois Sen. Barack Obama has his turn with David Letterman tonight, and he won't let the talk show host mess with his hair.

Obama is scheduled to appear tonight on the "Late Show with David Letterman" to present the show's famous Top Ten list.

The show was taped this afternoon, though, and after Obama presented the Top Ten Barack Obama Campaign Promises (No. 8 - Appoint Mitt Romney secretary of lookin' good. No. 3. I'll find money in the budget to buy Letterman a decent hairpiece.), Letterman wished him good luck with the campaign.

"Thank you so much, David, but you can't muss my hair," Obama said, according to a release by the show.

Former North Carolina Sen. John Edwards was more accommodating during an appearance on the show earlier this week.

In this photo released by CBS, host David Letterman, right, messes Democratic Presidential hopeful John Edwards' hair on the set of "The Late Show with David Letterman" in New York, Tuesday, Jan. 22, 2008. (AP Photo/CBS, J.P. Filo)

Oprah Winfrey, Bill O'Reilly and the possibility of an endorsement by David Letterman are among the subjects discussed when former North Carolina Sen. John Edwards appears tonight on the "Late Show with David Letterman."

Of course, not all of the discussion was as serious as Monday night's Democratic presidential debate in South Carolina.

And, at one point, Letterman tangled with Edwards' famous hair, according to quotes released by the show, which was taped this afternoon.

Letterman asked Edwards about the value of Winfrey's endorsement of Illinois Sen. Barack Obama.

"I'm kind of thinking you can do for me what Oprah's done for Barack," Edwards said.

Edwards and Letterman also discussed O'Reilly.

"He's a marvelous communicator, but he doesn't really care much about telling the truth," Letterman said.

"Yeah, I've noticed the same thing," Edwards responded.

Letterman: "Very entertaining, and I like when he's on the show, but if you say one thing..."

Edwards: "But most of what he says is crap."

Letterman: "I think you're right. There you go, exactly. I like how you think, Senator."

John Edwards may be having difficulty finding votes in the Democratic presidential race these days, but he's still getting plenty of tv exposure.

Edwards is scheduled to be on the "Late Show with David Letterman" on Tuesday and the "Tyra Banks Show" on Friday.

Perhaps Letterman could talk about the Top Ten Reasons John Edwards Is Still In The Race. Dome welcomes your suggestions.

Here's one to get things started: To meet Tyra Banks.