The 48-year-old daughter of the National Front's pugnacious founder Jean-Marie Le Pen has surged to the top of the poll ratings since conservative Francois Fillon lost his frontrunner status in a morass of scandals.
"This time it's for real, we're going to win. We've had Brexit, Donald Trump was elected and Francois Fillon has had his scandals... the planets are lining up," said Florent Erard, 27, head of the FN's youth wing in the Var, the region between the cities of Marseille and Nice.
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The Var is the FN's heartland - the party scored nearly 45 per cent here in the 2015 regional elections, compared with 28 percent in the rest of the country.
In towns like Saint-Raphael, between the palm trees, yachts and glasses of rose wine, Le Pen is preaching to the converted.
The biggest threat to her taking her anti-immigration and anti-European Union message to the Elysee Palace now appears to be Emmanuel Macron, the 39-year-old former investment banker who is pitching to the centre ground.
Polls that currently show the centrist Macron would beat her in the May 7 runoff vote are hotly disputed by Le Pen's supporters.
"Macron has no chance. The French people know where he comes from - he's the candidate of the world of finance while Marine is the people's choice," said Jean-Marc Micallef, 55, in his business suit and tie.
He and other supporters gathered last week for a campaign rally in Saint-Raphael, where Le Pen was treated as the president-in-waiting.
The FN's traditional rallying cry of "This is our land" rang out in a hall awash with red, white and blue French flags.
Apart from the hardcore of her supporters, others had come out of curiosity - many disillusioned by both the rightwing opposition and the Socialist government.
'Can't be worse'
"The FN has never governed (nationally), we don't know what it's going to produce. Perhaps it won't be better but it can't be worse than what we've got now," a 45-year-old man who gave his name as Philippe said.
Betty, an energetic 68-year-old red-head, said she used to back conservative former president Nicolas Sarkozy, who is still dogged by legal cases five years after leaving office.
"I am disgusted by politics. What else is there, apart from Marine? I'm a Gaul," she said, using the nickname of those who consider themselves to be "native French" rather than descendants of more recent waves of immigration.
Betty was keen to stress that she is no extremist.
"I'm a moderate," she said. "Look around you, there are no skinheads here, just people from all walks of life."
Le Pen has gone to great lengths to eliminate the openly racist and anti-Semitic fringe of her party, although critics point out that her remarks attacking Islam still receive the loudest cheers at her rallies.
"The FN electorate today is far more open than a few years ago," insisted Frederic Boccaletti, the FN's head in the Var.
"There are manual workers, office workers and people who have had trouble in their lives, but there are also professionals and heads of companies."
'We just want equality'
The FN's popularity in the south of France has its roots in the party's beginnings in the early 1970s as a refuge for paramilitaries who opposed Algeria's independence from France, granted a decade earlier.
When they left Algeria, many made their home in southern France.
They found a common cause with apologists for the wartime Vichy regime's collaboration with Nazi Germany and ultra-conservative Catholics.
At the picturesque port of Brusc, Le Pen had come to shake the hands of the market traders, and her pledges to cut taxes she says penalise small businesses received a warm welcome.
Yoan Jenais, a 19-year-old who runs a clothing stall, was delighted to have shaken hands with the candidate.
He said he was Le Pen's kind of voter.
"I didn't have a job so I have just set up my own company," he said. "But with all the taxes we have to pay, we can't keep the money we earn. It goes to the state."
And he was not afraid to speak his mind.
"I'm not racist, but when I see our parents working like dogs only to end up with nothing at the end of the month, while unemployed Arabs are walking around with iPhones... We don't want to be better than other people, we just want equality."
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