Four years ago Barack Obama promised to be a leader for all Americans. I remember listening to him in Chicago's Grant Park as he talked about a country full not of blue states or red states but the united states of America.

What a load of baloney.

Though re-elected as widely predicted last night, the real lesson for Obama is that he has utterly failed to fulfil the promise of his neophyte campaign in 2008. The great 50-50 nation remains terribly divided, and the President's ultra-negative campaign this time round was an attempt to exploit those divisions rather than heal them. He won by championing the very thing that he promised to end.

As the evening progressed, it became clear that the states Romney had to win to pull off a surprise triumph simply weren't breaking for him. Pennsylvania, then Michigan, then Wisconsin all went to Obama. These were states where Republicans always had only an outside chance of victory - but without Ohio, they desperately needed one.

When Ohio eventually went to the President, as recent polls suggested it was trending, the race was over for Romney. The Republican's claim late yesterday afternoon that he hadn't written a concession speech may have been true; but fairly early in the evening, he will have put pen to paper.

For him and the Republicans, the message of this campaign is extremely clear: America has an appetite for moderate conservatism, but the Republicans didn't want to provide it - and were wrong not to. Romney was an impressive candidate pulled to the right by a party gripped by theocratic dogma. His poll ratings peaked - as after the first election debate - when he played to America's moderate majority.

For the Democrats, this is a sobering result, and certainly not a vindication of Obama's Keynesian economics. He goes into his second term with a weak mandate for his social, economic and foreign policy.

For America as a whole, the negativity of this campaign, the division and animosity it has engendered, and the lack of a clear mandate for the President makes the urgently needed bipartisan co-operation of an Obama second term seem implausible. The coming fiscal cliff is just the beginning of what could be a years-long impasse.

Obama's first term was far more successful than his critics allege. But his second term will be far harder than his supporters pretend.