Kevin Phillips, D.P.P. (doctor of practical politics), has just given President Bush his annual checkup and finds the man in poor political health. In an op-ed piece in The New York Times, Phillips lists all the reasons why 1992 could be such a bad year for Bush (war abroad, recession at home) and ends by saying -- as any doctor should -- that his prognosis could be wrong: a "splendid success in the Persian Gulf" could make 1992 a splendid year for Bush.

Sentences like that chill me -- as columnist, citizen and the father of an 18-year-old son. I happen to think that war with Iraq is more likely than not and, further, that there are good and sufficient reasons to bloody Saddam Hussein's nose. But our domestic politics is not one of those reasons. And yet the suspicion is that national leaders sometimes turn to war when they get into trouble at home. Whether this actually happens or not, I don't know. I do know that Margaret Thatcher found the Falklands war politically bracing and that Ronald Reagan invaded Grenada right after the bombing of the Marine barracks in Lebanon.

What bothers me is the suspicion that if anyone would try the old foreign adventure diversion it would be George Bush. I say that because it's not clear what Bush might do when he's politically threatened. He is the one, after all, who beat Bob Dole in the 1988 New Hampshire primary by promising what Dole would not: that taxes would never be raised.

I do not for a moment think Bush would intentionally go to war just to boost his political Nielsens. I think, instead, that politics muddles thinking, that patience comes easiest to the confident and that only the politically secure can afford to err on the side of caution. In other words, I'm suggesting that Bush might, given some really low rating numbers, think in ways that he otherwise might not.

In his article, Phillips lists several reasons why Bush might be in trouble by 1992. The economy is teetering. The savings and loan crisis has yet to play itself out and, of course, Bush's performance as GOP leader has been inept. Only in foreign policy does his hand seem sure.

But there is a whole area that Phillips does not mention: Bush's lack of a constituency. For this president, things have only been good, and his approval ratings have only been high. Sooner or later, though, things are bound to get bad, and it is then that Bush will have to pay for his political opportunism. Neither a liberal nor a conservative -- and sometimes not much of a moderate, either -- he is the darling of no constituency. Unlike his predecessor, Ronald Reagan, Bush lacks the safety net of die-hard conservatives.

A president with no constituency is in a perilous fix should things go wrong. Such a predicament might color his thinking and encourage him to take risks out of political desperation. So Bush should be reminded that he has already set out when and under what circumstances the United States will go to war in the Gulf. The embargo must be seen to have failed, and Iraq must harm its hostages or engage in terrorism. The most recent condition added by the White House -- an increase in the looting and pillaging of Kuwait -- comes too late and is too elastic to serve as a condition for war.

Surely, you'd think, President Bush does not need to be told this. And yet, the invasion of Panama was launched with very little justification -- mostly, it seemed, because Bush was furious with Manuel Noriega. American troops were propelled into the Gulf for good reason -- but also, it seemed, because Saddam Hussein had angered Bush. "Iraqi lied," Bush sputtered after Saddam Hussein said he was pulling his troops out of Kuwait and then did not. He was so flustered he couldn't even get the name of the country right.

For Bush, Dr. Phillips' prognosis is downright chilling, and he might well yearn for that "splendid success in the Persian Gulf." Trouble is, no one can guarantee such an outcome. Anything less, especially if it's triggered by a pretext, might not only doom Bush's presidency but -- more important -- despoil American politics for some time to come. One Vietnam per half-century is quite enough.