Why won't Obama admit that the surge is working?

This may have something to do with it:

Female bombers struck Kurdish political protesters in Kirkuk and Shiite pilgrims in Baghdad on Monday morning, leaving at least 48 people dead and 249 wounded in one of the bloodiest sequences of attacks in Iraq this year.

One and a half years after the surge was implemented, Iraq remains one of the most violent places in the world. The surge only been a success compared to the bloodiest days of the conflict.