President Bush is saying the right thing about Iraq, which is that there is no easy fix for a war that his defense secretary correctly termed "a long, hard slog." But Bush is conveying this message in a detached way that upsets and angers growing numbers of Americans. The evaporation of political support at home is palpable. If the administration can't explain its war aims better, it may soon face a Vietnam-style tipping point.

First, let's look at what the president is doing right: At a time when anguished Americans are calling for a quick withdrawal from Iraq, Bush is telling them a painful truth.

"Pulling the troops out [now] would send a terrible signal to the enemy," he said last Thursday in Crawford, Tex. And Bush was right to avoid confirming any big reduction in U.S. troop levels in Iraq next year. Such a bring-the-troops-home message might buy him a respite in the public opinion polls, but it would undermine a fragile Iraqi government at a crucial time.

The administration's Micawberesque approach to the Iraqi constitution also seems correct, if somewhat disconnected from reality. Nobody knows if Iraq's fractious political leaders can agree, but the president was right to praise "the heroic efforts of Iraqi negotiators," even as they missed their Monday deadline for completing the constitution. Looking at the sunken, sleepless eyes of Zalmay Khalilzad, the U.S. ambassador to Baghdad, on television last weekend, it was obvious how hard he has been working to squeeze an agreement out of people who would otherwise be trying to kill each other.

Finally, I credit the spirit of realpolitik that undergirds the administration's upbeat talk. Last Sunday's story in The Post headlined "U.S. Lowers Sights on What Can Be Achieved in Iraq" mirrored what you hear privately from generals and senior officials. They know the war is going badly, and they have been crafting a strategy that puts more responsibility on Iraqis and less on U.S. troops. That doesn't mean an American withdrawal, but it does mean a lower U.S. profile, and a mission focused on training and advising Iraqi security forces.

A senior U.S. official in Baghdad explained the strategy to me this way: The most critical element in what lies ahead is Iraqi leadership. "We have now done enough for them in most areas, and it is increasingly up to them to carry this effort forward. . . . The pendulum is shifting from what we provide to what they do with it."

Now, let's look at what Bush is doing wrong. In speaking about Iraq to the nation, the president often seems tone deaf. Taking a nearly five-week vacation when U.S. troops are experiencing a living hell is a mistake. It reinforces what's cruelest about this war, which is that the soldiers in Iraq are doing all the suffering. Meanwhile, people back home go about their business. The president doesn't ask the country to sacrifice with taxes to pay for the war, or with an energy policy that would reduce our vulnerability to Mideast turmoil.

I have no doubt that Bush grieves for every fallen soldier. But he undercuts his leadership role with his seeming insensitivity to Cindy Sheehan. Whatever her personal quirks, this grieving mother has become a symbol for the families who are paying the real cost of the war. Once she began her vigil in Crawford, a presidential listening mission would have seemed like a no-brainer -- except at this White House, which appears to regard any concession to a critic as a mistake. Bush reinforced this appearance of insensitivity in a comment Saturday that was quoted by Cox News Service. He said that while he wants to be "thoughtful and sensitive" to people who want to talk to him, "I think it's also important for me to go on with my life."

A clear sign of Bush's failure to communicate effectively about Iraq comes from the pollsters. Newsweek and Associated Press polls taken in early August measured his job approval rating at 42 percent, the lowest level ever. Approval of his handling of Iraq was even lower -- 34 percent in Newsweek's sampling, 38 percent in the AP's. Anyone who doesn't think Vietnam when he sees those numbers doesn't have a good memory.

The measure of leadership isn't dealing with success but dealing with difficulty. Bush is now in that bitter cockpit. Somehow the president must find a way to level with the country and build support for a sustainable policy that puts more of the burden on Iraqis. A good start for Bush would be to come back to Washington early from Texas and start thinking how the nation as a whole can share in the sacrifices required by this long, hard slog.