A new report [PDF] from the Wisconsin Advertising Project, an effort by the University of Wisconsin to track political ad spending, reveals that the John McCain and Barack Obama campaigns have spent nearly $50 million to air over 100,000 general election TV ads over the past two months. Fully 10 percent of that total was spent by Obama in Florida, where McCain hasn't run a single spot since June 3. Another surprising finding: While Obama has cut the word "hope" entirely from his TV advertising, McCain has used it in over a third of his.

Ken Goldstein, director of the project and an expert in political advertising, spoke with NationalJournal.com about the study, both candidates' efforts to widen the electoral playing field and what to expect this fall.

Q: Besides both candidates spending more this election cycle, what other trends did your analysis turn up?

Goldstein: They spent more over a comparable time period. The general election in 2004 started much earlier -- started in March. But if you just look at June 3 to July 26, they're spending more this time.

I think one of the major, major things that really comes out is, there's been lots of talk about how 2008 is different; there's been lots of talk about Barack Obama expanding the playing field. But you look at the numbers, and once again it's those four big battleground states in the Midwest that are receiving the lion's share of the advertising: Wisconsin, Pennsylvania, Michigan and Ohio.

Q: What else has changed since 2004?

Goldstein: Obama has definitely expanded the playing field. States that did not receive advertising in the past are getting advertising, which is a different thing. But, as we note in the release, let's talk again in September or October and see how serious that is. We'll then really know if the playing field's getting expanded.

Q: Is that the usual pattern -- for campaigns to start with ambitious buys and then narrow the playing field later on?

Goldstein: Absolutely. You saw that in 2004. The ad buy always starts out bigger, and then, always, candidates make the tough, hard-headed decisions about which places really are competitive. And again, we saw that in 2004. We saw advertising in places like North Carolina and Virginia, Louisiana and Arizona, and we didn't end up seeing advertising in those states closer to Election Day in 2004.

That said, it is interesting. It is a big deal that Obama is advertising in these red states -- in [Georgia], in North Dakota, in Alaska, in Montana -- but we really won't know if it's serious for another couple weeks.

Q: Is it fair to say that McCain's concentrating on battleground states so far while Obama's spreading the wealth around?

Goldstein: Yes. The Republican spending -- the McCain spending -- is much more focused.

Q: Which is better strategy?

Goldstein: Both are smart for each candidate. Obama's got more money; he can afford to spread it around. John McCain's got to have more of an inside straight.

Q: Any reason to expect these figures to level off, or will they keep setting records throughout?

Goldstein: This is the low point. It's only going to get more intense.

Q: And more focused?

Goldstein: Well, we'll see. That's the big question. If it gets more focused, we'll know it's a very close race. If it tends to broaden, we'll know this race is going to be not as close.

Q: I was surprised to see that about a third of McCain's advertising was negative. Isn't it a little early in the race for that?

Goldstein: I'm surprised more of them aren't negative…. This election is not about John McCain. This election is about Barack Obama. You expect most of the advertising to be about Barack Obama, whether that's negative advertising by John McCain or positive advertising by Barack Obama.