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On the homefront, another battle ensues

A US soldier chatted with Iraqi boys as he patrolled Baghdad yesterday. How long US troops will be in Iraq remains unclear. (ALI YUSSEF/AFP/Getty Images)

WASHINGTON -- The Bush administration says it started the Iraq war, in part, to promote democracy. Now, the war's legislative endgame seems likely to become a civics lesson for the world.

The Senate's passage last week of a bill requiring the withdrawal of US troops in 2008 paves the way for a presidential veto and a long period of wrangling over whether any conditions should be attached to funding the troops. The process seems certain to continue into the summer, but could well drag on for the rest of this Congress and administration.

It will be unlike the prelude to the 2002 war resolution -- which sailed through Congress after an intense and heartfelt, but ultimately superficial debate and the yearly budget resolutions that have passed like clockwork. This year's debate promises to engage the American public in a detailed discussion, week after week, and to impose real accountability on all the lawmakers involved.

A quick review: The House and Senate have each narrowly passed bills to fund the troops for now, but set dates for withdrawal in 2008. Because the bills differ in their particulars, House and Senate leaders will have to come up with a unified version that should pass Congress in the next month or two.

Senate Republicans generally oppose any deadline for a pullout and still have enough votes to tie up debate through a filibuster. So far they have declined to do so. They seem to be figuring that it would be better to allow the bill to get vetoed by President Bush. The Senate would not have enough votes to override the veto, and discussion would quickly turn to whether to pass a new bill funding the troops, but without setting a date for withdrawal.

(Skipping the filibuster would also spare the Senate Republicans from having to explain every day why they favor keeping the war open-ended, which is increasingly unpopular. Instead, the onus for defending the open-ended war would be on Bush.)

But once Bush's veto was sustained, Congress and the president would be back at square one. There is only enough money in the defense budget to supply the troops until early summer, and Bush would no doubt contend that congressional Democrats are risking harm to the soldiers in order to score political points against the war.

Perhaps the sense of urgency to ensure the troops' safety would shake loose enough votes to secure a compromise measure. Equally possible is that the Democrats would choose to approve shorter resolutions funding the troops for weeks or months at a time.

Such a move would extend the debate into the fall and beyond. It would also have the split-the-difference effect of achieving many of the Democrats' aims, along with Bush's goal of giving his troop "surge" enough time to secure Baghdad.

The Democrats' professed aim in setting a deadline has been to pressure the Iraqi government to bring about a political solution.

Under the current situation, many Democrats contend, Prime Minister Nouri al-Maliki and other Iraqi leaders don't yet feel enough pressure to compromise. The best way to avoid a full-scale civil war would be for Maliki to make the politically dangerous decision to crack down on Shi'ite extremists, some of whom are part of his political coalition. Then rival Sunni Muslims might feel enough confidence in Maliki to join the government and keep their own extremists in line.

Such tough decisions, the Democrats maintain, will be made only when all responsible parties face the loss of their US protectors and confront the real possibility of having the government fall.

Were US troops to remain in Iraq on a month-to-month basis, Iraqis would certainly feel that sense of urgency, with or without a formal deadline.

Meanwhile, Bush would have a chance to argue that the troop increase is working; evidence of greater security on the ground could well persuade the American public of the necessity to keep troops in Iraq for a longer period.

Whatever happens, the long public debate in the United States will have the effect of forcing people to grapple with the hard realities in Iraq, including the real possibility of failure if US troops pull out too quickly.

Right now, the default position of the average American seems to have shifted from unthinking support of the war to unthinking support for a pullout.

A long political standoff in Washington would, at the very least, force some hard thinking on everyone.

Peter S. Canellos is the Globe's Washington bureau chief. National Perspective is his weekly analysis of events in the capital and beyond.