Hunch. On 8 November Gabriel Attal said it made no sense to step aside for Edouard Philippe, and Bruno Retailleau says he will stay in to the end without a vote.
The withdrawal market resolves on statements of Gabriel Attal, Bruno Retailleau and their parties: YES if by 28 February 2027, 11:59 pm Paris time, either of them publicly withdraws from the presidential race for any reason, including after losing a primary. If both are still candidates then, it resolves NO, and France 24, Politico Europe and Le Monde in English are the backups.
We looked for cases where parties of one French camp, the left or the centre and right, had a joint primary on the table before a presidential election. We found five such times since 2011, four on the left and one on the centre and right. The Socialist vote of 2011 was the first open vote of its kind in modern France. (The Guardian; The Guardian; BBC; Politico Europe; Le Monde)