Her supporters are confident, the French right wing are convinced she will be the woman to beat and pundits are already talking about the dawn of a new era. But, as Segolene Royal prepares for the final days of campaigning before the 220,000 members of the French Socialist party vote to decide their candidate for next year's presidential elections, it is increasingly clear that the fight will go right to the wire and could result in a major upset.

The elections on Thursday pit 53-year-old Royal, who has led polls throughout the summer, against Dominique Strauss-Kahn, a former Finance Minister, and Laurent Fabius, a former Prime Minister. One poll due to be published today will show Royal only a couple of percentage points ahead of her rivals. Newspapers are suddenly exercising a new prudence, after weeks of predicting a crushing victory for Royal. '[Relying on the polls] puts us on shifting, uncertain, unreliable and unpredictable terrain,' said Dominique de Montvalon, editor of Le Parisien.

The key issue is whether Royal can garner more than half the votes cast on Thursday and thus avoid a run-off which could see a dangerous deal between her opponents. 'If there is a second tour then we are in a whole new world of manoeuvres and deals and there is everything to play for,' said Michael Darmon, a senior political journalist and author. Some talk of an 'Anyone But Segolene' alliance.

Royal, a mother of four and the president of the Poitou-Charentes region, has suffered in a series of carefully choreographed televised debates between the three candidates. The confident and smooth delivery of Strauss-Kahn, 57, a former economist and convinced 'Social Democrat', has contrasted with the stilted speaking style of Royal, who has little experience of the raw reality of political rough-and-tumble. 'In the debates Strauss-Kahn was very good, open, informing and informed,' said Frederique Dabi, of the IFOP pollsters. 'That made a difference.'

Another blow came late last week with the broadcast of a video, filmed by an activist at a small meeting in January, in which Royal suggests that something should be done about French state school teachers who profit from a light workload to moonlight in the private sector, arguing that they should work a 35-hour week in their schools. Such ideas do not play well with the tens of thousands of teachers who are members of the Socialist Party.