Objectively (a word that appears to have disappeared from the socialists' dictionary), there are few discernible political differences between Ségolène Royal and Martine Aubry. The fight is almost entirely about personality. That perhaps helps explain the extreme rancour of the contest, with neither candidate willing to concede defeat.
In the early hours of Saturday morning, the rival camps were desperately contesting votes from as far away as New Caledonia and Guadeloupe while trading accusations of electoral fraud and threats of lawsuits. Well might one French newspaper wonder whether PS (Parti socialiste) now stands for Parti suicidaire.
The naive supposition would have been that this should be an ideal time to run a leftwing party, with capitalism in crisis and even free market champions such as Alan Greenspan, former US Federal Reserve chairman, admitting there has been something wrong with their conception of the economic universe. For years Europe's socialists have been calling for stricter regulation of lawless capitalism and a fairer redistribution of the fruits of globalisation. Should this not be their hour?
To be sure, many socialist parties in Europe have faced severe challenges in reinventing themselves following the collapse of the Berlin Wall. When the communist God failed it shook faith in minor deities such as socialism. The weakening of trade union membership in many countries has also removed an important institutional support.
In the 85 legislative elections in Europe over the past decade the political right has won 52.4 per cent of the vote, with the left accounting for 44.5 per cent. In 2007 the right was in power in 16 of the European Union's 27 member states. While many socialist leaders floundered to rethink their economic strategy, they channelled their radicalism into socio-cultural reforms. Student leaders of the 1968 generation who often emerged to run these parties championed issues such as gender equality, gay marriage and environmentalism.
Valid though these campaigns may have been, they were not the main focus of most working-class male voters who provided the bedrock of socialist parties during the 20th century. But these voters' core concern – preserving their jobs and income – presented socialist parties with a big strategic conundrum. Should socialist parties be about defending the jobs and privileges of “insiders” in the workplace, particularly in the public sector? Or should they be about opening up opportunities for the “outsiders”, very often immigrants, part-time workers and women?
Some socialist parties, in the UK and Spain for example, have found an answer. But the difficulty in resolving that dilemma elsewhere has led to a seepage of support towards extreme parties offering less ambiguous solutions. In Sweden the opposition Social Democratic party fears losing votes to the anti-immigrant right. In Germany the Social Democrats' support is leaking to the anti-capitalist Linke party.
The broader worry for France is that the socialists' psychodrama could turn into political tragedy. Few politicians are so in need of strong opposition as the headstrong President Nicolas Sarkozy. The absence of such opposition might further fuel extremist parties of which France has a bewildering choice.
If they need inspiration Europe's socialists should look to the one place they normally never seek it: the US. In spite of Republican claims, Barack Obama is no socialist. But he has just delivered a master class in political strategy that should educate all opposition parties. Three relevant lessons emerge. First, politicians must address their supporters' core concerns. Second, they must compete for new supporters by emphasising change. Third, they should project an image of calm, non-ideological competence.
The language of the market may not be very popular at the moment but it speaks to a fundamental political truth: the offer has to correspond to the demand. There is a huge demand for fresh, responsible, centre-left thinking and effective leadership across Europe. Can the political offer respond?
The writer is editor of the FT's Europe edition