I thought
this was a pretty good article summarizing some of the issues that are thought to play a role in presidential elections. Different indicators predict different outcomes. To summarize:
1. The economy: It's doing well enough that according to a model from Yale, Bush should win in a huge landslide. One exception in history: George H. W. Bush in 1992.
2. Incumbent approval rating: Incumbents don't win if their job approval ratings are below 50%.
Here's a website that tracks all the different polls and keeps an average. Current average: 45%. And the trend has been downward over the past several months, another indicator.
3. War: Presidents have always been re-elected during a war. Of course, LBJ didn't run because of Vietnam, so he's not counted.
4. Ohio: The Republican has to win Ohio to win the general election. Bush won 50-46 over Gore in 2000.
It appears to be about the same as back then as I post this.
5. Southern Democrat: After Kennedy, Democrats have to be from the South to win. And southern running mates don't help (Dukakis). Being a southerner doesn't guarantee a win - LBJ the southerner dropped out, Carter the southerner lost re-election, Gore the southerner lost - but no Democrat from outside the South has ever won.
6. Height: Taller candidates win, in all case but Gore, who was taller than Bush (though he won more popular votes). Kerry is 6'4", Bush's height is said to be 5' 11 3/4"

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