Surges and surges

I confess to being a little confused. Obama says he would still oppose the surge in Iraq, and that the surge did not contribute significantly to recent improvements there. But he wants to do a surge in Afghanistan. Why will that surge improve things? If the economic, political and security situation in Afghanistan is that much worse than in Iraq, isn't a surge even more likely to be a perilous and risky endeavor? And if the situation is that much better, isn't it even more superfluous?