In July 1948, a dispirited Democratic party assembled in Philadelphia to nominate President Harry Truman in what was assumed would be a losing campaign against Republican Thomas Dewey. But Truman was having none of it. On a sweltering night, he rose, looked at his running mate Alben Barkley, and began his speech with “Senator Barkley and I will win this election and make these Republicans like it”. He then demanded the Republican-controlled Congress return from its summer recess and pass all the legislation it was promising to enact once Dewey was president.

It was not merely the start of a remarkable turnaround in Truman’s electoral prospects, but the response to the intensely partisan atmosphere that had developed in Washington after the war.

It’s a different Democratic convention in 2012. The party has benefited from rousing speeches from the first lady and former president Bill Clinton, probably the greatest instinctive politician America has seen since FDR. The contrast with a stolid, painfully homogenous Republican convention that seemed dominated by angry white males has been significant. As Crikey hit deadline Barack Obama, a man of gifted and sometimes inspiring oratory, was delivering another memorable acceptance.

But the malicious air of partisanship is the same — or worse.

For too much of his presidency Obama has failed to heed the lesson of Truman’s: that at some point partisanship becomes so obstructive in the political process that co-operation and appeals to national interest no longer work and confrontation is the only way forward.

Moreover, Obama faces far worse circumstances than Truman. US politics is now riven with a partisan ferocity that has not been seen since the 19th century. As many of its more moderate and traditional leaders attest, a lunatic fringe has overtaken sections of the Republican Party. And they have done so at a deeply worrying time: the US economy is only feebly recovering from the disaster of the financial crisis; its fiscal circumstances are unsustainable; its unemployment rate remains stubbornly high. Worse, corporate interests have a tighter grip than ever on the federal political process.

If re-elected, Obama can’t govern in the same way as he has in his first term. More gridlock, more partisanship, more angry rhetoric will be the result, rather than substantive progress on issues of critical importance to America and the world. Obama must reach beyond the wild enthusiasm of the convention hall and bring American voters with him in a way that will enable him to successfully challenge the strident partisanship and bitterness of his opponents.