He has told us. The strategy is for victory. Most Americans do understand that, and most Americans want that from their CIC.
BTW, the President has not expanded power, he has utilized all available avenues within the law.
Let me make this a bit more concrete. In WWII, it was understood when Allied troops entered Berlin, the war in Europe would be over. It was understood that the war in the Pacific would end with the surrender of Japan. Even in the Cold War, it was understood that it would be over with the end of Soviet Communism. In the war on terror, who exactly is going to sign the surrender agreement on behalf of the terrorists? What's the terrorist capital for US troops to overrun? As best as I tell, the war will be over when the President declares the war to be over and given that it is the President who is asking for expanded powers, I see a huge conflict of interest.