Socialists capture the French imagination – but at what cost?

The Socialist Party's open primary on Sunday was a triumph. More than two and a half million people took part. There were queues to cast votes even in the blue-collar areas and troubled racially mixed suburbs, where the largely middle-class Parti Socialiste has not been a force for decades.

All French mainstream parties, including President Nicolas Sarkozy's secretive and patronising UMP, will feel obliged in future to throw their choice of presidential candidate open to a wide electorate. But democracy is dangerous stuff for political leaders. The old smoke-filled rooms were safer for them.

The open Socialist primary – the first by any party in France – was supposed to do two things: create a broad-based movement for a centre-left victory in the presidential elections next spring and unite moderate, left-leaning and centrist voters behind a single candidate.

The first round of the "citizens' primary" was a popular triumph but threatens to split the Socialists down the middle. The opinion-poll front-runner François Hollande took just over 39 per cent of the vote. The party's leader, Martine Aubry, came second with just under 31 per cent. A first-round lead of 8.5 per cent should, in theory, give Mr Hollande a solid platform for victory in the two-candidate second round this Sunday. But where will the likeable, moderate, reliable, plodding Mr Hollande find the extra votes?

Manuel Valls, 49, the most right-wing of the six first-round candidates, took 5.7 per cent of the vote. He has already advised his supporters to back Mr Hollande. Ségolène Royal, 58, the failed Socialist presidential candidate in 2007, scored a humiliating 6.9 per cent. She is the estranged ex-partner of Mr Hollande and the mother of his four children. She now preaches a flaky, soft-edged leftiness with is far distant from the realistic but uninspiring message of "Hollandisme". She detests her former partner; she also detests Ms Aubry. How will she advise her followers to vote next Sunday?

The great surprise of last weekend's vote was the nearly 17 per cent which went to the glibly eloquent Arnaud Montebourg, 48, who campaigned against banks and globalisation and for a new French constitution. In theory, the Montebourg vote should transfer en bloc to Ms Aubry, who ran a more traditional left-wing campaign than Mr Hollande.

Mr Montebourg plans to demand concessions on state regulation of banks and financial markets and EU protectionism against Asia before deciding which of the remaining candidates to support. Some of his voters may switch to Mr Hollande as the candidate more likely to beat President Sarkozy. Harder left Montebourg voters may not bother to turn out a second time.

Mr Hollande yesterday appealed to all candidates, including Ms Aubry, to continue the non-aggression pact that they almost observed before the first round. Their only real enemy, he said, is Nicolas Sarkozy. No Socialist should open wounds which will be impossible to heal before the presidential election next April and May.

Ms Aubry may take the view that non-aggression is fine for a front-runner but not so good for a challenger. Will she go for the jugular in the next few days? Will the second-round televised debate promised for tomorrow night even take place? Will Mr Hollande, or Ms Aubry, be forced to throw lumps of red meat to the left which will rot their chances with a wider electorate next spring? On balance, Mr Hollande should win a narrow victory on Sunday, although he is unlikely to have the overwhelming mandate to defeat President Sarkozy that he had hoped for.

But the huge turnout last Sunday revealed a hunger for a more transparent kind of democracy in France. It also confirmed a widespread desire to be rid of Mr Sarkozy, not just on the left. The popular success of the first round of the primary suggests that the centre left has a real chance to claim the presidency next May for the first time since 1988. The popular verdict – or rather the lack of a clear, popular verdict – suggests that the Socialists lack the charismatic standard-bearer that they need to be confident of victory.