WASHINGTON – When the Bush administration invaded Iraq seven years ago, it pledged to leave behind a democracy that would be a model for the entire Middle East. Instead, it now appears that the United States will leave behind a big question mark.

Sunday’s parliamentary elections in Iraq will start the clock on the withdrawal of U.S. troops, with 50,000 soldiers remaining in an advisory role after Aug. 31 and all of them gone by the end of 2011, if current plans hold.

The elections are, in a sense, the final act of a U.S.-led invasion that has cost nearly 4,400 American lives, at least 100,000 Iraqi ones, as much as $3 trillion and untold political capital.

Senior U.S. officials and top generals, using football terminology, like to speak of the American effort in Iraq as being in the “red zone,” close to the goal line of a reasonably stable and democratic country after years of struggle and sacrifice.

Others who have spent significant time in Iraq, however, say that the country’s future, while vastly more hopeful than it was four years ago, is nonetheless still in doubt.

“This can go either way. And it can go either way for a long time to come,” said Ryan Crocker, the U.S. ambassador in Baghdad from 2007 to 2009.

Violence in Iraq is down markedly, but political, ethnic and secular reconciliation has remained elusive. The fault line between Sunni Muslim Arabs and Sunni Kurds still tears at the country’s northern tier. Iraq’s neighbors, particularly Shiite Muslim Iran and Sunni-dominated Saudi Arabia, see it as a potential regional battleground.

The elections, in which 6,200 candidates are vying for 325 parliament seats, will open a months-long effort to form a new government. That path will be strewn with pitfalls and could stretch beyond the self-imposed Aug. 31 U.S. deadline for withdrawing combat brigades.

The situation is so fragile that President Barack Obama is hearing more calls to consider slowing the troop withdrawal if Iraq takes a turn for the worse.

During a recent visit to Washington, Army Gen. Raymond Odierno, the commander of U.S. forces in Iraq, signaled that he might ask Obama to keep one combat brigade, about 3,000 troops, in the powder-keg city of Kirkuk, on the Arab-Kurdish fault line, after Sept. 1.

However, Obama, who pledged during his election campaign to withdraw U.S. forces from Iraq, appears determined to keep to the schedule no matter what.

Sometime this spring, there will be more U.S. troops in Afghanistan than there are in Iraq for the first time since March 2003. There are now 96,000 in Iraq and 78,000 in Afghanistan.

Wayne White, the State Department’s principal Iraq analyst from 2003 to 2005, said American influence in Iraq had plummeted and there was little point in extending the U.S. stay.

“If Humpty Dumpty is going to fall apart there’s very little that the United States is going to be able to do about it,” White said. What the United States will leave behind “is not predictable. But that shouldn’t stop us from expediting our withdrawal.”