France's radical left-wing Socialist, Benoit Hamon, Sunday easily defeated former Prime Minister Manuel Valls in race to become party candidate in forthcoming presidential election in April and May this year. The 290,000 votes the former economy minister received in the primary's first round were expected to help Hamon defeat Valls in the runoff.
Almost a million people went to vote in the Socialist Party primaries, compared to 400,000 in the first round.
But he was not a party member, and has spurned the Socialist primaries that Valls and Hamon are contesting, having launched his own centrist political movement last summer.
By 1600 GMT, at least 1.3 million people had voted in 75 percent of polling stations which had reported turnout figures, organizer Christophe Borgel told reporters.
Hamon, a 49-year-old former education minister, needs to lure back Socialists who have defected to communist-backed Jean-Luc Melenchon on the party's left and to independent Emmanuel Macron in the center. Financial prosecutors are investigating an allegedly fake but handsomely paid job as a parliamentary aide held by this wife, Penelope.
Mr Hamon's signature proposal for a 750 euro "universal income" that would be gradually granted to all adults also proved a campaign masterstroke.
At a campaign rally in Paris on Sunday - where a boisterous crowd gave Penelope Fillon a standing ovation and chanted her name, Mr Fillon said, "We have nothing to hide".
"Through Penelope they are trying to break me", he said.
He added that Hamon's task was now to reunite the socialists.
In such a complex political landscape, some voters cast ballots strategically. "He's not a serious candidate".
Sunday's victor is now calling for unity in the Socialist party and urging support from other political factions on the left in order to take on the strong Conservative Republican party led by Francois Fillon and also fend off an electoral challenge from the extremist right-wing National Front, led by Marine Le Pen.
Early polling has suggested that the Socialist nominee will struggle to advance from the presidential election first-round in April to qualify for the runoff in May.