Its interesting that in last nights presidential debate Mitt Romney appeared to make substantially more promises about what he will do if elected president than Barak Obama made. I could be wrong on this, but it seems like when Obama was campaigning and debating in 2008 he made plenty of promises of what he would do, some broken promises of which are plaguing him now.
In other words, what I’m seeing is that the challengers in these elections make plenty of promises, while the incumbents are much more cautious. But the irony here is that if the incumbent is re-elected, it doesn’t hurt him four years later if he breaks his promises (since he won’t be running again), while the opposite is true of the challenger.
I’m making this generalization from very few data points, so it could be bunk, although at least in this case it seems to be true.