It is a lie that Congress must pass a bill to end the occupation of Iraq. The occupation can be ended with an announcement by Congressional leaders that there will be no more funding. Any proposal to fund it can be blocked by 41 senators. Bush has plenty of money for withdrawal and could be given more for that exclusive purpose. When your television tells you the Democrats need 60 or 67 senators to end the occupation, your television is lying to you.
Speaker Nancy Pelosi and Senate Majority Leader Harry Reid could if they wanted announce today that the House and Senate will no longer bring to a vote any bills to fund anything other than withdrawal. They have many colleagues already on board with that position, not to mention two thirds of the country. It would take 218 signatures on a discharge petition to force a bill to the floor of the House without Pelosi's approval. It is unlikely enough Democrats would oppose their party to fund Bush's war in that way. In the Senate, Reid alone could refuse to bring a bill to the floor, or another senator could put a secret hold on a bill. And, while not all bills can be filibustered (appropriations bills can be, budget reconciliation bills cannot), you can hardly claim you need 60 votes to get past a filibuster without admitting that with only 41 you could launch your own filibuster and that with 51 you could defeat any bill. Once you understand the goal as blocking bills rather than passing them, the number of allies you need shrinks dramatically.