After French President François Hollande's shock announcement that he will not run for re-election, the battle on the left has begun in earnest. A Socialist primary election is scheduled for the end of January but its winner will have to contend with two emerging rivals, Jean-Luc Mélenchon on the far-left and Emmanuel Macron in the centre. This division bodes ill for the left in the presidential election, especially when compared to the unity on the right and the far-right.