Steve is just chomping at the bit to let the Shia militias loose on Al-Anbar province. He is just an un-reformed cold war warrior at heart.
I actually have a different viewpoint. Siding with the Shiites will just ensure Shia dominance over Iraq. That will result in an Iraq which is allied with Iran, which also has a shiite majority. That would be unpalatable to the U.S., Israel, Saudi Arabia and yes, even Syria.
A different strategy would be to back the Sunnis. They already have a strong base in Al-Anbar. It may be a tough sell, since Sunnis have been bearing the brunt of american counter-insurgency efforts, but they also know that a permanent Shia-run government in Iraq is not in their best interests.
A Sunni led Iraq, at this point, would not be pro-U.S., but it would counterbalance Iran, which would, more or less, restore the pre-2003 balance of power in the region.
Now some people may ask: "Why go to war to replace one Sunni dictatorship with a different Sunni dictatorship?" To which I can only reply: "Welcome to the wonderful world of middle eastern politics."