Last Sunday President Obama visited New Jersey to campaign alongside the incumbent Democratic Governor. At the last of five rallies he addressed that day he reached wearily for a well-used metaphor about a mop. He was happy to mop up the mess left by his predecessor, he said, but was troubled by a “collective amnesia” setting in about the mess. His main message was “remember Bush”. But he and voters have been so intensely focused for the past year on a floundering economy and a failing war effort that the collective amnesia has spread. His other message was: “Remember me.”

The floodlit walk to the victory podium in Chicago, and the extraordinary story embodied by the winner, are already distant memories for most American taxpayers. Mr Obama’s victory lap lasted a few hours and the 12 months since have been a marathon exercise in crisis management. Signs that the US is emerging from that crisis, at least at home, are an important achievement for which the President deserves much credit. He was emphatic and decisive on the need for a colossal stimulus package, however history judges its effectiveness. But rescuing the economy was never the change he promised the youthful alliance that swept him to power.

That change is only now coming into focus as specific policies. Any fair assessment of Mr Obama’s first nine months in office must acknowledge regrettable delays in framing health reforms and costly agonising in the White House Situation Room over how to prevail in Afghanistan. Presidents Franklin Roosevelt and Lyndon Johnson achieved far more in their first months in office. But this much is also undeniable: Mr Obama’s ambition is undimmed and his potential to transform both America’s self-image and its image in the world remains hard to overstate.

There was never an obvious timetable or strategy for extending health insurance cover to the 46 million Americans who lack it. Nor could Mr Obama hope to conjure a congressional majority in support of mandatory carbon emissions caps merely by wishing it. Presidential power is notoriously circumscribed. Given the soaring expectations of his supporters, they were bound to feel disappointment a year into his Administration.

Yet he is closer to signing comprehensive health reforms than any of his predecessors and has diametrically reversed Washington’s stance on the torture and detention of suspected terrorists. He has also broken with a generation of received wisdom on American policy toward Iran, taken a dramatic step to “reset” US-Russian relations and handled Washington’s crucial relationship with Beijing with a maturity that belies his scant foreign policy experience.

Mr Obama’s critics say he is less comfortable wielding the executive pen and demanding his way, than he is holding a microphone and hosting a decorous discussion. They have a point. They also say that playing the “Bush card” is old. This, too, is true. But the Obama card is still new and powerful. It is worth remembering that the man running the most imaginative US Administration in living memory is the grandson of a Kenyan goatherd. That his personal story has been largely forgotten in the tumult of politics speaks volumes about the gravity of the challenges he faces and the seriousness with which he is addressing them.