Ivan Eland believes that the administration is thinking troop withdrawl primarily due to domestic political pressures:

In Iraq, like everywhere else, if things don’t add up, it is safe to assume that politics is involved. Although the insurgency in recent months has worsened, Gen. George W. Casey, the commander of U.S. forces in Iraq, astonishingly claims that security in Iraq has improved and that substantial U.S. troop withdrawals are possible by as early as next spring. What gives? The congressional elections in 2006.

Although Bush administration officials have implied that demands by Democrats for a U.S. troop withdrawal timetable are “unpatriotic” and “aid the enemy,” when electoral politics is involved, the administration is all too willing to predict troop reductions during a specified time period. They know that the Democrats will try to make political hay—probably starting around next spring—from the growing unpopularity here at home of the continued occupation of Iraq. By showing some incremental and token progress toward getting out of the quagmire, the administration hopes to contain the damage Democrats could do on this issue at election time.