The Democratic leadership may believe--rightly or wrongly--that such a strategy would entail unacceptable political costs. But that's very different from being unable to affect policy. To insist, as many media outlets have, that the Constitution makes it impossible for Congress to stop the war obscures the actual choices facing the nation--by confusing "can't" with "won't."
The point made by these media outlets again and again is that the Democrats have little power to affect policy in Iraq because it would be difficult to pass legislation over a potential Republican filibuster, and even harder to pass a bill over a presidential veto. This sentiment is also voiced by many Democratic politicians, many of whom consider themselves opponents of the war. But passing a filibuster- or veto-proof bill is not their only option.
Newsweek's Howard Fineman declared that the Democrats' powerlessness was built into the constitutional system on NBC's Chris Matthews Show (9/2/07):
Politically, what the president has been trying to do is to keep discipline among the Republicans because as long as he can keep most of the Republicans in the Senate, in the House with him, there's no way to overturn the policy because of the way the Constitution reads.... I hate to keep coming back to the Constitution. Sixty votes to stop a filibuster, 67 to overturn a presidential veto in the Senate.
This sort of analysis was used to explain the Democrats' need to compromise with Republicans, watering down a firm withdrawal date in the hopes of winning bipartisan support. "Senior Democrats now say they are willing to rethink their push to establish a withdrawal deadline of next spring if doing so will attract the 60 Senate votes needed to prevail," reported the New York Times' Carl Hulse (9/5/07). "Democrats would need to lure the 60 senators in order to cut off a likely Republican filibuster."
This approach was endorsed in an Associated Press report (9/11/07) by Matthew Lee:
If Republican support for the war holds, as it might for now, Democrats would have to soften their approach if they want to pass an anti-war proposal. But they remain under substantial pressure by voters and politically influential anti-war groups to settle for nothing less than ordering troop withdrawals or cutting off money for the war--legislation that has little chances of passing.