The Commission on Presidential Debates has made clear that the candidates' campaigns have requested a change in the topic scheduling of the debates. Evidently, the results of the negotiations include that the first debate will focus on foreign policy while the final debate will focus on domestic policy. Until recently, however, the order for the topics had been the other way around. According to a friend who had worked on the Commission for Presidential Debates for over thirteen years, this renegotiation was at the request of the Obama campaign. This was a mistake.
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This was a mistake for two reason.
The first reason this was a mistake is because the first debate is the one that influences the election the most. This was the case in 1960 for Kennedy and it was the case for Kerry in 2004. Because the first debate has the most impact on voter decisions isn't a problem all by itself. Instead, when combined with the second problem, Obama causes himself to undermine the potential impact of the debates in a race filled with undecideds (nearly 18% of the electorate).
If one follows priming theory, the candidate's position on the issues most salient to them when they vote will determine their selection. So, if voters tend to side with McCain on energy and foreign policy issues, and if energy and foreign policy issues are their number one concerns on election day, people will break in McCain's favor (this is a hypothetical, but research supports this). Well, the issue most salient to voters right now are domestic economic issues, and Obama just pushed those items back in the debate cycle, when the fewest number of viewers tune in.
One might respond that making the final debate focus on domestic issues puts it closer to election day. The problem with that argument is that most of the themes and issues that the media will spin will be determined well before then. The least watched debate will do too little to affect that. Even Nixon got better as the debates went on, but it didn't help him after the first debate performance.