The infamous $400 haircuts that 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 battles, 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.

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

Smith confirms it on his blog:

"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," Smith wrote.