0151 GMT July 16, 2019
The vote on Sunday will pick two candidates to progress to a second round on January 29.
A total of seven candidates are vying for the nomination, namely Francois de Rugy, Manuel Valls, Arnaud Montebourg, Sylvia Pinel, Benoit Hamon, Vincent Peillon, and Jean-Luc Bennahmias.
Two candidates, Valls and Hamon, have gained better results in opinion polls against next-in line Montebourg and the others. Valls, a former prime minister, and ex-education minister Hamon are neck-and-neck at 28 percent, with former economy minister Montebourg trailing at 24 percent.
President Francois Hollande is himself a socialist, and observers say public opinion may be tilting to the right after almost five years of his presidency.
The chances of a socialist being elected as the next French president in the upcoming election are slim, and polls indicate that the socialist candidate will be eliminated in the first round, which is slated for April 23.
Analysts predict there will be no serious socialist contender in the upcoming presidential vote and the race will be between the conservative ex-premier Francois Fillon, far-right leader Marine Le Pen, and Emmanuel Macron, a socialist-liberal-turned-independent.