Obama Still Has Big Advertising Edge

That was critical for Obama, Goldstein said, because he is not nearly as well known as Clinton. Alan Solomont, a top fundraiser for Obama, said the campaign has always recognized that Clinton's near-universal name recognition is a daunting challenge.

"We're running against a quasi-incumbent who's known everywhere," he said. "In virtually every state, we start from a standing position. We essentially start behind. That's why being able to advertise is so important."

Robert Zimmerman, a New York public relations executive and key Clinton supporter, said that any assumption that Obama's advertising advantage will prove decisive moving forward represents "an inside-the-Beltway mind-set."

"There are so many ways the messages are getting through," Zimmerman said. "With free media, news coverage, Internet ads, rallies, direct mail -- I think this whole notion that the number of ads you have up determines one's viability, it's obsolete thinking."

Clinton's latest advertising push has for the first time included negative spots. Two ads have knocked Obama for declining to debate her in Wisconsin. Obama responded to the first negative ad with a spot that said, "After 18 debates, with two more coming, Hillary says Barack Obama is ducking debates? It's the same old politics of phony charges and false attacks."

The Clinton team fired back yesterday with a commercial that says, "Barack Obama still won't agree to debate in Wisconsin. And now he's hiding behind false attack ads. Maybe he doesn't want to explain why his health-care plan leaves out 15 million people and Hillary's covers everyone."

Goldstein said he was surprised that Clinton has only now started to aggressively attack her opponent. He compared the circumstances to the 2004 contest between President Bush and John F. Kerry. Bush was far better known and used his ads to attack the senator from Massachusetts. Kerry ran mostly positive spots, Goldstein said.

"At this point, this campaign is really about Barack Obama now. He's still not as well known. Her job really is to define him," he said. Until now, Obama's financial edge has not allowed her to do that.