When the state legislatures decided to push the presidential nominating process into the early months of 2008, one wonders what they expected. Whatever it was, the two parties have settled on spectacularly different ways of filling the nearly eight months between now and Election Day.

The Republicans, probably by pure accident, agreed on their nominee almost at the very start. The conservatives who dominate the party had no favorite for the nomination, and it wound up going, very early and almost by default, to a distinguished but distinctly moderate conservative, John McCain, who will appeal mightily to independents in November. Meanwhile, he will generate what excitement he can over his choice of a vice president.

The Democrats, on the other hand, are split down the middle, with half of them supporting Hillary Clinton and the other half backing Barack Obama. Both candidates have already won important primaries, and neither has yet pulled significantly ahead. The fight, therefore, promises to continue right through the rest of the primary season and quite possibly to the floor of the August convention. Many Democratic leaders fear that this will lead to bad blood and damage the party's chances in November. But the Democrats are famous for waging nasty intramural battles and then kissing and making up in time for the election. Whether they will do so this time remains, in the grand old expression, to be seen.

As I have said before, 2008 is by rights a Democratic year. The Republicans have occupied the White House for eight years and controlled Congress for six of those years. What's more, the economy is, at best, sluggish, and the Iraq War, while going better than it was, is broadly unpopular and constitutes a millstone around the GOP's neck. The voters could hardly be blamed for thinking it's time to turn the rascals out and give the other side a chance. Historically, this has almost always been the case in comparable situations.

But McCain is an attractive guy, seemingly well-suited by his record as a soldier to lead the country at a time when terrorists are active all over the world and have already demonstrated an ability to inflict serious damage on the American heartland. Clinton, on the other hand, has no record of coping with global terror, or for that matter with any other military menace.

Neither, to be sure, has Obama, whose experience in federal government is limited to not quite three years in the U.S. Senate. But it is the fear that he could convince voters that he is, at least potentially, a heavyweight on security issues that makes Republicans hope devoutly that Clinton, rather than Obama, will be facing them next fall.

So a great deal depends on whether Obama can depict himself plausibly as a battler against terrorism in the next eight months. And the importance of that question will be increased greatly if these next eight months witness any spectacular increases in terrorism.

Therein lies the deadly danger, to the Democrats, of the long stretch of time between now and Election Day. Is it safe to assume that the terrorists on the Pakistani-Afghan frontier, and in their safe houses in Europe and elsewhere, have no plans for staging some ugly surprises in the United States between now and November? A sophisticated observer might think it is in their best interests to lie low until Clinton or Obama is elected. But are the terrorists that interested in the differences between (say) Obama and McCain? Or do they, in their generosity, despise the Republicans and the Democrats equally?

Just suppose the Democrats nominate Obama, and he embarks on the final campaign slashing McCain as a clone of George W. Bush, presiding over a dismal economy. And then suppose that, in early October, a terrorist attack on Washington slaughters a dozen or so senators, or leaves the Capitol dome tilting at a slight angle. Would that influence the electorate? You can bet your bottom dollar it would.