This is a partial transcript of "The Big Story With John Gibson," Sept. 30, 2004, that has been edited for clarity.

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HEATHER NAUERT, FOX NEWS CORRESPONDENT: Well, there's actually a new FOX poll out that says that seven in 10 voters won't change their decision after the debates, but there's another chunk of voters who say that they're likely to change their minds after they see Bush and Kerry in action tonight.

So, the big question, of course, is: what on earth is going to sway voters' decisions?

Diana Carlin, a debate specialist joins me from Kansas City. That's a big question: what is it that the candidates need to do Thursday night to try to win these swing voters?

DIANA CARLIN, UNIVERSITY OF KANSAS COMMUNICATIONS PROFESSOR AND DEBATE SPECIALIST: Well, the undecided voters (search) are undecided partially because they're hearing a lot of heat instead of seeing much light. So they're going to want assurances on the terrorism issue, on a resolution to Iraq; and they're there to compare who has the better answers at this point in time.

These are people who probably haven't been paying as close attention as all of us have and so they want the debates to give them more than that 15-second sound bite or the 30-second negative spot.

NAUERT: So, tonight is not about the base, it's not about shoring up your base. It's rather, grabbing, seizing, and getting commitments from the people who truly aren't certain?

CARLIN: That's true. And as you said, about three out of every 10 are either leaning towards someone that aren't firm or they're truly undecided. And what the debates do for that other 70 percent is they will listen and they'll hear what they want to hear.

Typically people who are supporting Bush will come out thinking he did the best; people supporting Kerry will think he did the best. Those people who are looking for some very specific things, they're going to be listening carefully to hear those.

NAUERT: Can you put some of these numbers into perspective for us, because one of these polls that you and I are talking about says that 18 percent of people are likely to change their minds after watching the debates. Is that a lot?

CARLIN: Oh, absolutely.

NAUERT: Because on the other hand, it's the 70-some number that says they won't change their mind. So, is it a glass half empty or a glass half full?

CARLIN: Well, it's a matter of you don't need to change all of the votes if there's only an 8 percent difference right now. If there are 18 percent who may change their minds and you have an 8 percent difference, you don't have to change the other 70 percent.

That's been the case with every election where it's mattered: the Kennedy-Nixon clip you had was a good example. That was one where it was 100,000 votes difference in the popular vote, about a million and a half people said they'd changed their minds. It was enough to make a difference. 

NAUERT: What message seems to play better among this sort of, general audience? Is it the message of the optimist or is it the more pessimistic message?

CARLIN: It's definitely more an optimistic message. I think Ronald Reagan (search) was a good example of that in 1980 and also '84. I think you also saw that in '92. People want a leader who they have confidence in; they want to see someone who they feel is going to make the right decisions and inspires them to feel comfortable about their situation right now.

NAUERT: What as an expert in this — and I bet you know offhand, are so incredibly familiar with so many of the debates throughout history — but what will you be looking for tonight?

CARLIN: I look at these probably very differently than everybody else. I'm looking more at knowing what their game plans are going in: who executed it better. I'm also going to be trying to think the way that undecided voter does and who's coming across to reassure me more, to give me the kinds of answers that I'd want if I were undecided.

NAUERT: What is the best mindset to go into a debate with?

CARLIN: What I usually tell people, especially undecideds, are know what it is you're looking for. What are the answers you're after and listen for those?

But more importantly, look for that person who you think is going to be there over the next four years to be in tune with what the American public needs, to look at our position in the world, given this is an international debate tonight, and who's doing the best job of convincing you that he's the better person for the job.

NAUERT: Now, just briefly, if you're talking to the candidates and you're giving them advice, what kind of mindset are you telling them to go in with?

CARLIN: Well, if it were President Bush, he's obviously the incumbent, he has an advantage, he has the record to point to. People don't have to work as hard to imagine him as president. If you're John Kerry, you have a lot of negatives out there you have to deal with. You have to show the leadership potential, you have to show that you have some definite ideas about what to do, deal with the flip-flop issue, and then move on and give people a positive vision also.

NAUERT: All right. Diana Carlin, thanks a lot. Appreciate it.

CARLIN: Thank you.

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