Things are not working out as Democratic congressional leaders expected. For the first eight months of this year, they struggled to find some way to shut down the American military effort in Iraq.

They took it for granted that we were stuck in a quagmire in Iraq, with continuous high casualties and very little to show for them. They pressed hard to get the Republican votes they needed to block a filibuster in the Senate and were cheered when some Republicans, like John Warner, seemed to lean their way. They worked hard over the August recess to pressure Republican House members to break ranks and vote with them.

But the Republicans mostly held fast. Senate Minority Leader Mitch McConnell skillfully parried their thrusts in the Senate. House Minority Leader John Boehner persuaded most House Republicans to hang on. Then, over the summer, the news out of Iraq started to get better.

Mainstream media types tend to think that, while rising casualties from Iraq are legitimate news, falling casualties are not. But even so the word got out: The surge strategy was producing results. Anbar province, given up for lost in 2006, turned peaceful and cooperative in 2007. U.S. casualties and Iraqi civilian casualties were down. Brookings scholars Michael O'Hanlon and Kenneth Pollack, no fans of the administration's conduct of the war, announced on July 30 (in the pages of The New York Times, no less) that this was "a war we might just win."

The congressional Democrats got ready for one more push in September. But the testimony of General David Petraeus and Ambassador Ryan Crocker cut the ground from under their feet. Now, Senate Majority Leader Harry Reid (who declared last spring that the war was lost) and Speaker Nancy Pelosi seem to have thrown in the towel. The Democratic Congress will not use its power to appropriate to end the surge or to bring the soldiers home.

That leaves the left wing of the party angry at its leaders and the party split on the war, much as it was in 2002, when about half of congressional Democrats voted to authorize military action.

The Democrats here suffered from a lack of imagination. They could not imagine that the United States military could perform more effectively in 2007 than it did in 2005 and 2006.

George W. Bush seems to have had a similar lack of imagination until the November 2006 elections woke him up. But he chose a new commander and a new strategy, and things have changed. Democratic leaders have acted on the assumption that the status quo of November 2006 would persist indefinitely.

The Democrats have found themselves on the defensive on other issues, as well. Last week, the House Democrats were forced to delay a vote on their version of the revision of the Foreign Intelligence Surveillance Act, which among other things would have prohibited surveillance of communications between suspected terrorists abroad and persons in the United States without a court warrant.

The House Democrats were responsive to left-wingers' theoretical concerns about abusive surveillance and unconcerned that most voters don't want the National Security Agency to hang up when Osama bin Laden calls the United States. In any case, they were undercut when Senate Democrats agreed to a revision that did not contain that provision and others unacceptable to the Bush administration.

The House Democratic leadership also backed down last week from its determination to bring a resolution condemning the Turkish government's massacre of Armenians in 1915-16. The Turkish government took umbrage at this, and its parliament voted to authorize military action in Iraq's Kurdish provinces against anti-Turkish Kurdish guerrillas -- a nightmare scenario in the one part of Iraq that has been consistently peaceful and pro-American since 2003.

Senior House Democrats like John Murtha and Ike Skelton said the resolution was a bad idea, and Nancy Pelosi reversed herself (as Speaker Dennis Hastert did on the same issue in 2000, at the request of Bill Clinton).

Democrats are coming face to face with the fact that there's a war on -- and that Americans prefer success to failure. If the choice is between stalemate and withdrawal, as it seemed to be in November 2006, they may favor withdrawal; but if the choice is between victory and withdrawal, they don't want to quit -- or to undermine the effort.

Last week, Democrat Niki Tsongas won a special election with only 51 percent of the vote, in a Massachusetts district where John Kerry won 57 percent in 2004 and would have run much better in 2006. History doesn't stand still -- we're not in 2006 anymore.