On the campaign trail Le Pen has positioned herself as a protector of France who would pull the country out of the EU, slash immigration, make it harder to get French nationality and crack down on suspected Islamists.
"French people have the feeling of being dispossessed of their identity, of their social security system and their sovereignty," the National Front (FN) leader told BFM television on Wednesday.
Even though she is widely expected to lose in the May 7 run-off if she makes it that far, her strength in the polls has left many worried about the future of France and the European Union.
AFP has spoken to Le Pen supporters across France about why they have chosen to back her:
"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...," said Yoan Jenais, 19, who runs a clothing stall in Saint Raphael in southern France.
"We don't want to be better than other people, we just want equality," he added.
Daniele Pubert, a retired 65-year-old cleaner from La Roche-sur-Yon in Brittany, western France, said she is voting FN because she wants "a big change".
"We, the French, are no longer the priority," she said.
"Marine will be able to get the country back on its feet. Migrants are in unfortunate (situations), but there are people from France struggling and they must be helped urgently. To not do so would be an injustice," said Dorothee, 38, a prison guard in the northern town of Bapaume.
Behind the xenophobic and anti-Islam words of Le Pen voters, there is often another driving sentiment, Christele Marchand-Lagier, an FN specialist at the University of Avignon in southern France, told AFP.
There is "a feeling of being pushed aside, abandoned".
Attack 'made up my mind'
French voters have so far been more concerned about unemployment and their spending power than terrorism or security, opinion polls show, though analysts warn this would change quickly in the event of an attack.
Still, security is a worry for the French in the wake of the string of Islamist-inspired attacks that have killed more than 230 people since the beginning of 2015.
That worry has been a boon for the far-right party, which has made public safety one of its priorities.
"With me (in charge) there would never have been migrant terrorists at the Bataclan and Stade de France," Le Pen said, referring to sites targeted in the 2015 terror attacks in Paris.
"The attack made up my mind," said Andre, 48, a resident of the Riviera city of Nice who plans to vote for Le Pen after the Islamist carnage in his city last July that killed 86 people.
Nice's local branch of the FN says it saw a "10 percent boom in membership after the attack, then a progressive increase in the following weeks."
'One we haven't tried'
The depressed former coal mining town of Henin-Beaumont has had an FN mayor since 2014 and some residents are happy with their leadership.
"Like a lot of people here I used to be a leftist but I switched camp and I'm not ashamed to say it. We were betrayed, we were robbed. This mayor, he does what he says he will do," said Elisabeth Develter, a 70-year-old retired supermarket worker.
"I support Marine. She is the only one we haven't tried," 58-year-old truck driver Michel Cadour said in the central France village of Varzy.
"Mainstream politicians don't care about rural voters. They're too busy looking after their interests in town," he said.
'Where is the progress?'
France's unemployment rate has hovered near 10 percent in recent years, despite promises from its last two presidents to spur growth.
"I voted for (Nicolas) Sarkozy, we got nothing. I voted for (Francois) Hollande, we got nothing. So, I'm going to vote for Le Pen and we'll see," said Pasa Ertugrul, 29, from the eastern town of Brousseval.
"Around here the factories are closing, so where is the progress in France?" he asked.