Yet on the most important issue facing ordinary Americans – the economy – Mr Obama is shaping up to be one almighty let down. As mid-term elections loom, there is visible panic among Democrats at the administration's failure to get to grips with deep-seated economic problems.

Tony Blair, who came to power on a similarly intoxicating wave of public euphoria, at least had the following wind of "The Great Moderation" – a virtually unprecedented period of economic stability and growth – to disguise the disappointments and repeated policy mistakes of his premiership. There was no such golden windfall to act as a prop for Mr Obama: the economy he inherited was toxic from top to bottom. The country was on the brink of a potentially severe depression; it was fighting two, essentially unaffordable wars; the budget deficit was spiralling out of control; jobs were being shed at the rate of nearly one million a month; public debt was on a catastrophically unsustainable trajectory.

Nobody could have expected Mr Obama to fix all these problems in the 20 months he has been in the job, but they might by now reasonably have expected at least a glimpse of the promised sunlit uplands.

There is no such vision on the horizon. Joblessness remains stubbornly high and, far from becoming self-sustaining, the recovery shows signs of stalling. In short, Mr Obama's economic policies have failed, or at least that is the growing public perception.

For me, it is still too early to make that judgment; as it happens there was modest encouragement from yesterday's US employment data. But many investors have made up their minds. Rightly or wrongly, yields on Treasury bonds are at levels that discount a depression.

Rarely have Americans felt so down in the dumps; collectively, they seem to have lost their innate sense of self-belief and optimism. Not since the 1930s has the American dream looked so forlorn. What's gone wrong, and why has the patient proved so unwilling to respond to the extraordinary fiscal and monetary medicine applied?

To supporters of deficit spending, it's not that the fiscal stimulus isn't working, but that it was always insufficient to do the trick. To them, Mr Obama should have done much more in his early months when he still had the political credit to take bold steps.

Most of us have something of a problem with this argument. The near $1 trillion fiscal stimulus Mr Obama applied could hardly be described as underwhelming. Indeed, it was without precedent in terms of size; very probably it was the most that was politically feasible at the time, too.

How much good it has done is anyone's guess. Supportive economists claim it averted a depression, but it doesn't seem to have done much for jobs. Beyond the ever widening deficit, there has been little discernible effect.

You can argue until the cows come home on the merits of further deficit spending, but even if Mr Obama were to take the view that he has to do more – as the White House's departing chief economist, Christina Romer, said he should this week – he almost certainly won't get that chance. Mr Obama is not just down in the polls; on present voting intentions, the Democrats will lose the House in the coming mid-terms, and possibly the Senate, too. Even if he wanted to spend more, he's not going to be allowed to. Anxiety about the deficit is stymieing the White House's jobs agenda.

Even Democrats shrink from overt support for more spending, and beyond some targeted measures which would carry no net costs, the president seems to have accepted there's virtually no room for manoeuvre. Already evident political stalemate will turn into gridlock after the mid-terms. Mr Obama won't be allowed more fiscal stimulus, and nor, despite their demands for deficit reduction, will his Republican opponents allow him to raise taxes to put public debt on a sustainable footing.

Now it may well be that the severity of the economic headwinds renders almost any further policy response ineffective, but politicians are not forgiven for impotence. On the main challenges facing his administration, Mr Obama falls between two stalls – he seems incapable of tackling either unemployment or the deficit.

Whatever his other achievements, Mr Obama will go down in history as the worst president since Jimmy Carter if he cannot make headway on either of these issues. It's hard to be optimistic. Mr Obama looks like a beached whale. As Tony Blair observes in his new autobiography, there is nothing quite so painful as high expectations dashed by harsh political and economic realities.