When the man they call No Drama Obama met the Clinton Psychodrama in the Democratic primary campaign, it was bound to produce an epic for the ages. The iron self-discipline of the long-shot pretender proved just enough in the end to overcome the front-runner whose strengths were undermined by the self-indulgent incontinence characteristic of the Clinton political machine. It seemed a fitting catharsis for the modern Democratic Party when he won the primary.

And when Senator Obama cemented his victory over the summer by declining to offer her his vice-presidential slot, it appeared to douse once and for all the last embers of the Clinton family's ambitions.

From the Democratic convention, the word went out that Hillary - and even Bill - was finally resigned to a late life of public service, toiling diligently in the vineyard of President Obama's America, seeking nothing more than to serve the new leadership, loyally committed to a cause greater than their own self-advancement.

All right, maybe that was all a bit of a stretch. But with his election as president, Mr Obama surely demonstrated that the victory was his and his alone, and that the country would be spared the prospect of yet another chapter in the Clinton saga that has dominated American politics for the best part of two decades.

And yet, here we are, a couple of weeks after that historic election, and once again all we are talking about is - the Clintons.

It would be an understatement to say that the sudden and unexpected emergence of Senator Clinton's name as the President-elect's apparent choice to be his secretary of state has caused consternation among some of Mr Obama's most loyal followers.

They are aghast that, as they see it, having wisely steered clear of giving her the vice-presidency, their man has supposedly offered her what is, in all but the constitutional succession stakes, a much bigger job. The State Department is a vast bureaucracy that supports a Cabinet member who is the most frequently seen face of America in the world. One can only guess, by the way, what Joe Biden, the man who got the vice-presidential slot over Senator Clinton, in large part because of his foreign policy credentials, now thinks about the idea of sitting quietly in his vice-presidential office suite watching Mrs Clinton strut her global stuff on television.

Not that even Senator Clinton's strongest critics deny that there are good reasons for her to get the job. First, few doubt that she is qualified to do it. She demonstrated on the campaign trail the breadth of her intellectual reach, a genuine depth of knowledge on global affairs and the sort of energy needed for someone who might fly half a million miles in the course of a year.

What's more, it is not as though there was a great range of alternatives. John Kerry, first mooted for the job a while back, famously aloof and arrogant, might have proved a diplomatic disaster. Bill Richardson, the New Mexico Governor with the colourful past, was too risky for the global stage. Richard Holbrooke, the self-appointed dean of Democratic diplomacy, had alienated too many of the Obama foreign policy team through his disdainful dismissal of their inexperience during the primary campaign. Tony Lake, Senator Obama's principal foreign policy adviser in the campaign, said he didn't want the job. Tom Daschle, the former leader of the Senate Democrats and an early adopter of the Obama brand, seemed to lack the global heft to be the public face of the new president.

So why not go with the best qualified candidate? And one other reason for Mr Obama to pick Mrs Clinton was that there was no better way to signal the preternatural self-confidence that has propelled him so far so fast in politics than by nominating his former rival to the biggest government job outside the White House.

So what's the problem? The problem is that should Senator Clinton, by any chance, be looking to make her own mark in the next four years and subtly distinguish herself from the new president, there could hardly be a better perch from which to do it. Differences between the two during the primary campaign were sharpest over foreign policy. Mrs Clinton denounced Mr Obama's pledge to meet foreign dictators without preconditions and generally mocked his inexperience.

The Obama foreign policy team fought back by undermining Senator Clinton's claims to foreign policy experience. Gregory Craig, one of the earliest Obama supporters, who had himself served in the Clinton State Department in the 1990s, penned a famously damaging memo that dismantled all the instances of Mrs Clinton's professed involvement in key foreign policy decisions in that Administration.

What most troubles Obama loyalists is that a Clinton nomination threatens to destroy a feature of the new president's politics that has been essential to Senator Obama's success: its cohesion and unity of purpose. The No Drama title applied not just to the candidate but to the whole campaign, from the start. It was remarkably free of the usual tensions that permeate all political campaigns, at least in public.

And that is the risk in the Clinton nomination, should it come. You don't even have to believe that Senator Clinton will actively try to undermine the president. She's surely a loyal Democrat and a patriotic American who in any case understands that active pursuit of her own cause would do her more harm than good.

The problem is that the Clintons really can't help it. For all their protean talents, for all their political and intellectual skills, they have an unrivalled knack for making politics into very personal theatre, an unerring capacity to turn any crisis into a drama, one in which they play all the central roles. Another example of the Clinton dynastic principle at work was the appearance of Chelsea on the campaign trail with her mother. Who is to say that she won't continue the family tradition?

Nothing better illustrates the tendency than the very fact that the political class in Washington has spent the past week excitedly digesting the possibility of a Clinton nomination, while America's Other First Family semi-publicly debates the merits of it.

For President Obama the opportunity in Secretary of State Clinton is knowing that his message to the rest of the world is in capable political hands. For No Drama Obama, the danger is that American foreign policy for the next four years becomes the gaudy stage on which the latest act in the engrossing saga of Clinton Agonistes is played out.

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