President Bush has shown that he can win an election by mobilizing his political base. But can he win a war that way?

The most striking poll findings after the president's speech to the nation on Tuesday concerned who watched Bush in the first place. According to a Gallup Poll for CNN and USA Today, 50 percent of those who chose to listen to Bush were Republican, 27 percent were independents and only 23 percent were Democrats.

Frank Newport, Gallup's editor in chief, said the usual party split in the country as a whole was about one-third for each party and a third independent -- a finding confirmed by five Gallup Polls conducted in June.

In other words, a large share of Bush's congregation belonged to the choir. Many Democrats don't want to listen to him.

Newport says the partisan skew in Bush's television audiences has been visible for most of his presidency; there was also a partisan slant to Bill Clinton's audiences, though it was less pronounced than Bush's.

But the most troubling finding for Bush may be an indirect indicator from the Gallup survey. Before the speech, Gallup's interviewers identified 933 people who said they intended to watch the president. The night Bush spoke, the pollsters reached 648 of these people -- but only about half of them, 323, actually tuned in. Newport's conclusion: "It just suggests to us that it ended up being a less compelling occasion for Americans than other occasions."

According to Nielsen Media Research, Bush's speech was watched by just over 23 million people in roughly 18 million households. As one marker, the season finale of "American Idol" drew 30.3 million viewers. True, the president picked a tough time to make his case. People have other things to do in the summer, and many no doubt watched or read the speech (or reports about it) later. Still, this was the smallest audience for any major Bush speech. The president's address announcing a new policy on stem cell research in August 2001, the previous low, drew 8 million more viewers.

Bush's supporters could argue that the lack of interest suggests that the Iraq war has yet to arouse passionate opposition. But the obverse is also true: There is very little enthusiasm for this war. Support or acquiescence might not survive much more than another year, less if there is a significant run of bad news.

There is also this: Democrats are no longer afraid to criticize Bush, as they were for much of the two years after the attacks of Sept. 11, 2001. Indeed, the reaction to the president's repeated mentions of the attacks underscored the dissipation of national unity over the past four years.

In the past, the mere mention of that galvanizing day would unify the country. Bush and his lieutenants gave it another shot, but his five mentions of Sept. 11 brought jeers, not cheers, from Democrats. "It shows the weak ground that they're on that they would mention the sacred ground of 9/11," House Democratic leader Nancy Pelosi said in an interview.

She was expressing a view held across her party, but she was also reflecting a critical political fact. Except for Bush's loyalists, Americans are increasingly inclined to view his Iraq policy as quite apart from the terrorist attacks. By using the attacks on the World Trade Center and the Pentagon in a highly partisan way during his first term -- recall the role of Sept. 11 during last year's Republican National Convention -- Bush has squandered his ability to invoke the moment in a nonpartisan and patriotic way.

In recent weeks, administration loyalists have repeatedly expressed alarm that Americans are forgetting "the lessons of 9/11." That is not the case. It is the administration that has forgotten those lessons. They had to do with the country's capacity to come together in the face of a common threat and Bush's choice for several months afterward to act as a national leader rather than a party leader.

But the relentless partisanship returned. It did wonders in reelecting Bush and creating a Republican congressional majority. Now come the costs: When a wartime leader speaks and much of the country doesn't choose to listen, it's more than a political problem.

Many of us who are Bush critics may welcome his falling standing in the polls, but we certainly don't welcome the prospect of a disaster in Iraq. A president who has wrung about all he could from his base needs a broader audience if he wants to win a war.