French Prime Minister Manuel Valls has announced his intention to stand for president.
The 54-year-old socialist, who has been in office since April 2014, will step aside from his current role on Tuesday to focus on his campaign.
Valls will face other contenders in the Socialist primary next month.
He will run to replace current President Francois Hollande, a fellow socialist, who announced last Thursday he would not stand for re-election in 2017.
"Yes, I am candidate for the presidency of the Republic", Valls said in a speech to supporters.
Last week, incumbent president Hollande revealed he would not be extending his four-year stay at the Élysée Palace.
Hollande, who was elected in 2012, has battled deep unpopularity among the French public.
His ratings suffered significantly in the aftermath of terrorist attacks in both Paris and Nice.
Valls said he wished to unite the left of French politics.