The leading contenders in the Socialist presidential primary -- party leader Martine Aubry, her predecessor Francois Hollande and defeated 2007 candidate Segolene Royale -- came to La Rochelle in feisty mood.
France's current centre-right leader, President Nicolas Sarkozy, is languishing in opinion polls and the economy in flatlining, so whichever Socialist emerges from the primary ought to be in with a chance in May.
But the party has been left in disarray by the spectacular burnout of its hero, former IMF chief Strauss-Kahn, who has been cleared by a New York court of a sexual assault charge, but whose political credit is spent.
Strauss-Kahn's passport was returned to him by US authorities on Thursday, but the remaining Socialist candidates hope that his eventual return to France will be sufficiently low key so as not to disrupt the primary.
In the meantime, the gloves have come off in their own battle, despite repeated pleas from the party for a good clean fight that will leave the centre left united behind a single unbloodied flag-bearer.
"When I took over the Socialist Party we were an object of pity ... We were not ready to rule," declared Aubry, hailing her own three-year-old leadership of the party, but also stabbing her predecessor Hollande.
"If I have decided to run for president, it's because I'm determined to win. I think that today I'm the best placed to represent a project for our country," she said, in an interview with France Inter radio.
Aubry -- 61-year-old mayor of Lille and daughter of former chairman of the European Commission Jacques Delors -- is in combative mood, despite insisting that "debate is not combat", and despite bad news from pollsters.
An IFOP survey published by the daily Le Monde on the opening day of the party conference placed Hollande way out in front among first round primary voters at 42 percent, followed by Aubry on 31 and Royal on 18.
This was Hollande's chance to repay Aubry, urging candidates to behave "responsibly", and adding: "I am a bit more responsible than the others because, more than them, I'm seen as someone who could actually win."
But Hollande -- a 57-year-old party insider and the former partner of his latter-day rival Royal -- may have a harder battle than he thinks.
Firstly, as Royal was furiously quick to point out, the poll was based on a tiny sample of only 404 likely voters, and thus has a wide margin of error.
Secondly, the race is over two rounds, and in a Hollande-Aubry run-off the pair come much closer, well within that margin of error, at 53 to 47.
And thirdly, it is hard to project exactly which voters will take part in the votes on October 9 and 16. The primary is open to any registered voter who pays a nominal one euro fee -- not just Socialist Party members.
The idea is to unite leftists, Greens, Communists and others who oppose Sarkozy in a broad opposition coalition, but this may lead to unpredictable voting patterns and even tactical voting by Sarkozy supporters.
It is true that many general polls suggest Hollande -- seen as a down-to-earth and congenial figure, on the centre of the centre-left and untainted by any previous time in office -- has the best shot at beating Sarkozy.
But he is bitterly resented by many of the party faithful, including many of the now leaderless fans of Strauss-Kahn and -- for personal as well as political reasons -- by his former lover Royal.
So, as the party holds three days of debate in La Rochelle, will Strauss-Kahn be the ghost at the feast? His New York scandal made him politically untouchable in the country, but he still has back-room influence.
One senior party figure who talked to AFP thought not: "DSK will pass messages, but he won't swing things one way or another."
Indeed, two of DSK's former allies are standing themselves as no-hoper outsiders -- positioning themselves for the 2017 race -- and another has joined the camp of his former mentor's great enemy Hollande.