Leading article: A presidency unzipped: history will not judge him kindly

It seems unlikely that President Clinton will be impeached. Even if he has told - and encouraging the telling of - the little lies that are needed for the functioning of a society built on the myth of serial monogamy. But this week's revelations have delivered a jolt to the presidency that will change history. Until this week, Bill Clinton was destined to be remembered as a moderate reformer, a "borderline third tier" President, in the words of his former adviser Dick Morris. Now he will go down as Slick Willy, a man who made himself look ridiculous and demeaned the office of President because he could not keep his trousers up.

That is probably all that history - popular history anyway - will have room for: a couple of lines in a school textbook, and a photo of Bill and Hillary. (She, incidentally, is now more likely to be captioned as a stoic wife than the woman who tried to reform health care and failed.)

For us, who have to live through these times, however, the question, "Does Clinton matter?", is more complex, pressing and relevant. It is fit to ask: What difference would it make if Clinton fell? In order to answer that question, we have to assess both Clinton's record and - a few years early - the prospect of an Al Gore presidency.

So far, Clinton's record has been disappointing. He was elected on two important pledges. One was to give America a national health service; the other was to "end welfare as we know it". Both are still as far from fulfilment as ever. The nation has probably decided that it doesn't really want a comprehensive health service after all, while welfare reform has turned out to be much more difficult than the simplicities of campaign rhetoric could ever encompass.

This second failure has obvious and ominous implications for Tony Blair, whose New Labour platform was partly inspired by the 1992 US presidential campaign, in which Bill Clinton ran as a "New Democrat".

However, it must be remembered that the US constitution is very different from ours. Much of the responsibility for welfare lies with the states rather than the federal government. It has long been observed that in times other than those of national emergency, the President's main power lies in the realm of persuasion, symbol and rhetoric.

In these areas, Clinton has been the President for the time. A large rambling mansion of a man, a likeable, loose- fitting amalgam of good intentions, policy ideas and testosterone, he has proved surprisingly popular. Like Mr Blair, he has been able to find the words to unite a nation in shock: the Oklahoma bombing was his death of a princess. But that is as far as the transatlantic parallels go. Where Mr Blair is straight and puritanical, Mr Clinton is loose, erratic and a philanderer.

The present crisis has arisen almost inexorably from the pressures of the American political system. It requires candidates who are larger than life, over-endowed with personal charm in order to raise vast sums of money, and with mass-media sex appeal to cut through the clutter of the television age. It is bound to bring forth over-sexed men with an instrumental view of the opposite sex.

At the same time, it demands adherence to a moral code that owes more to New England in the 1600s than to the reality of modern life in Peoria, Illinois. The American media are still surprisingly prudish in matters sexual, but they are no longer so deferential as in the 1960s, when John Kennedy complained that he got a headache if he didn't incessantly satisfy his lusts.

None of this seems to matter much to the American electorate. Clinton has presided over stable economic growth and, partly as a result, has cut the federal budget deficit. He is, in fact, one of the most popular Presidents ever. But Dick Morris did not list Dwight Eisenhower as one of the 18 "great" Presidents, not even of the third tier. "He didn't do anything. Popularity doesn't get you on the list."

Clinton, then, will go down as a President who reflected America rather than changing it. His sexual appetite stands as a vivid analogy for America's gross desire to consume material goods and petroleum. The contrast with his Vice-President is stark. Al Gore is a buttoned-up puritan, who would have been satisfied burning witches righteously in Salem. He wrote a book about America's responsibility to save the planet from environmental disaster. And he took office with a plan to "reinvent government", to turn the incubus of state bureaucracy into an agent of change. That didn't happen, partly because Clinton, loose, creative and brilliant, dissipated the administration's political energies in too many large and unsuccessful policy initiatives.

It is a good thing that the US constitution does not allow the President too much scope for screwing things up. But it looks as if it will be up to Mr Gore to test the potential power of the presidency to change America for the better. That will probably not happen ahead of schedule, but it does no harm that this week's events have turned attention to the future. If the most powerful nation on earth can both be better governed and more environmentally responsible, that would be a step forward for the world.