The poll numbers are alarming -- 77 percent approval in a Post survey a scant two years ago and 48 percent approval at the beginning of last week. So it isn't surprising that the president's speech last Tuesday at Fort Bragg was designed to reverse the disastrous trend.

What was surprising to me is how badly George Bush misdiagnosed the reasons for the plummeting numbers. He seemed to think the numbers are down because Americans have forgotten Sept. 11 -- five separate mentions -- or because we've lost our will to take a stand or because we have become complacent about terrorism.

No. The numbers are down because the American people have come to believe that the administration has no plan for dealing with either Iraq specifically or terrorism generally -- beyond "staying the course."

I happened to be in Cleveland the day before the speech, and an editorial in the Plain Dealer pointed out, with unusual force and clarity, what the president needed to do:

"No more vague platitudes . . . about how 'Our troops are fighting these terrorists in Iraq so you will not have to face them here at home.' . . . No more patent falsehoods about the 'last throes,' " the newspaper urged, as though anticipating the president's remarks. "The Bush administration has to level with the American people on how long and how costly this war could be." The paper specifically rejected the call for a date certain for withdrawal. But it urged the White House to "climb off its high horse to reveal exactly how long U.S. troops could be in Iraq."

In Austin, Edwin Dorn of the University of Texas was making the same point a different way. Dorn, who was undersecretary of defense during the Clinton administration, called for the president to choose the "responsible middle ground" between a firm deadline and a "fatuous formulation such as 'We'll stay until the job is done.' "

That middle ground? A clear exposition of just what the job is. Otherwise, neither the American people nor the administration will know when it's been accomplished.

What is the job? At first, Dorn reminds us in an op-ed he wrote for the Austin American-Statesman, it was to eliminate Saddam Hussein's weapons of mass destruction and to punish him for supporting the Sept. 11 terrorists. "The first part of that job was achieved before the first cruise missile was launched," Dorn says, "because Saddam had no weapons of mass destruction. The second part was misguided, because Saddam's relatively secular regime had virtually nothing to do with Osama bin Laden and al Qaeda. So in a sense, President Bush was right when, a few months after the invasion, he declared 'mission accomplished.' "

Unfortunately, just as the administration felt constrained to keep coming up with new reasons for launching the war -- a University of Illinois student says her research turned up 23 post-Sept. 11 rationales -- it seems to keep finding new reasons to stay.

Dorn lists a few of these:

* Restoring at least some of the Iraqi infrastructure -- water supplies, communication grids, power plants and oil production facilities.

* Creating -- virtually man by man -- a security force to replace the one we dismantled.

* Building a new government, with open elections and a new constitution.

* Planting the seeds of democracy in Iraq as a first step toward spreading democracy throughout the Middle East.

* Defeating the insurgency without letting it turn into a civil war.

The numbers Bush desperately wants to reverse are not evidence of flagging American perseverance so much as of mission fatigue. What people want to know is which of these goals are of greatest importance, and how much progress on them it will take to constitute success.

Nor is that the end of the questions left unaddressed at Fort Bragg.

How, for instance, does the administration weigh the balance between going to war in Iraq as a move against international terrorism and the fact that the war has turned out to be a major recruitment tool for the terrorists? Even if you've been stung once, it doesn't necessarily make sense to take a stick and whack the hornet's nest.

In what way does our engagement in Iraq make us stronger and more likely to be taken seriously? Wouldn't an adversary's best guess be that we are less likely than before to use our military to protect our worldwide interests?

With the Army still struggling to meet recruiting goals, where will we find the soldiers to replace those already exhausted from two or more tours in Iraq?

And Dorn's last question: "Does the president expect that Congress will continue to write blank checks, onto which he scribbles $80 billion every year?"

willrasp@washpost.com