Obama's "so sue me" taunt appeals to everyone -- except vulnerable Democratic incumbents

On one hand, Democrats need motivation, so a pitched battle between the president and the Republican House reminds voters what the election is about—candidates fighting for the middle class versus partisan Republicans. It also makes the fight personal: Democrats are more likely to have Obama’s back if they’re properly focused with him as the targeted party.

On the other hand, this taunt is more likely to motivate the Republican base than Democratic voters. The anger at Obama that motivates Republican voters is a more powerful force than the threat of a Republican majority or promise of legislation that might help the middle class, both of which are possible election outcomes that might motivate Democratic voters. If you’re an endangered Democrat this cycle, you probably live in one of the seven states in play that Obama lost to Romney, which means the field is already tilted against you. Plus, there’s always the danger that a national debate about the president and what he has and hasn’t done distracts from your effort to keep the race about local issues and the weakness of your opponent.