Benoit Hamon won the left-wing primaries on Sunday evening with almost 60 percent of the vote, beating former Prime Minister Manuel Valls and potentially giving a major advantage to independent candidate Emmanuel Macron.
In electing Hamon, left-wing voters have chosen to mark their opposition to the government's liberal line. A former education minister under Manuel Valls in 2014, Hamon was sacked after four months because of disagreements over the economic measures of Valls and President Francois Hollande.
Since then, he has actively opposed the government with other lawmakers in a group called "Frondeurs" (insubordinates). Over the past few years, the group has refused to vote for the budget and filed a motion of censure (which failed by two votes) over a controversial labor law.
With his leftist program, Hamon represents the heart of the socialist ideology in France but also underlines the different views within the party. His main task will be to reunite the wider left divided between the "Frondeurs", the extreme left wing and the more liberal incumbents embodied by Hollande and Valls.
However, Hamon failed to mention this more liberal side in his victory speech Sunday, saying that "from Monday, I will offer Jean-Luc Mélenchon and Yannick Jadot (extreme left-wing and green party candidates respectively) to build a consistent majority". A broad consensus is badly needed for the left to stand a chance in the run-off in the presidential elections in May. The left or center-left has currently four different candidates, with Emmanuel Macron, France's former economy minister, running as independent.