France is "coming to the end of a political order that started in the 1980s", said political scientist and pollster Jerome Sainte-Marie.
Over this time, the reins passed back and forth between the Socialists and the Republicans (previously known as the UMP), with the far-right National Front (NF) looking on from the sidelines.
But with each swing of the pendulum, real change has become increasingly elusive, "alongside a growing exasperation in the face of the economic crisis", Sainte-Marie said.
Current polls show that NF leader Marine Le Pen, 48, and centrist Emmanuel Macron, a 39-year-old former Socialist minister who founded his own movement last year, will duel in May's final vote.
As well as a prevailing mood of disillusionment, which reflects longstanding trends showing the French are worried about the direction of their country, there are also short-term reasons to explain the possible shift.
The Socialists are deeply divided after the unpopular five-year term of incumbent President Francois Hollande and struggling to rally voters around their candidate, the former education minister Benoit Hamon.
Despite being picked in a primary vote in January by party activists, Hamon's economic programme and tax-and-spend proposals are divisive: popular with left-wingers but seen as making him unelectable by others.
Communist-backed candidate Jean-Luc Melenchon, who rejected an alliance with Hamon, is also threatening to split their vote. He enjoys about 10 percent support, according to surveys.
Most importantly, the Republicans' candidate Francois Fillon, the clear frontrunner until the end of January to be president is mired in a fake jobs scandal.
He was charged with several offences including the misuse of public money on Tuesday after employing his wife in parliament but has insisted on staying in the race.
The scandal has upended the campaign and has provided an opening for the energetic Macron.
"Their recipes have simply failed," argues the centrist, economically liberal and pro-European Macron, who says he wants to lift up a middle class that has been "neglected" by both the left and the right.
Globalisation v 'losing out'
Meanwhile Le Pen, the anti-immigration, anti-EU candidate, scores points by railing against the establishment "elites".
The rhetoric of the NF does not come in a vacuum but on the heels of Britain's shock vote to leave the European Union and Donald Trump's stunning US election win.
Unlike Fillon, who has had to battle to stay in the race, Le Pen has carried on unscathed despite her own fake jobs scandal as an MEP.
A recent survey found more than one in three respondents -- 36 percent -- think Le Pen has new ideas for solving France's problems.
"We are seeing a democratic shift in France and the world... towards populist culture and the collapse of the culture of parties," historian Pierre Rosanvallon wrote in the centre-left daily Le Monde.
The new rift, according to Sainte Marie, will be between those who are benefiting from globalisation and "those who feel they are losing out".
This is Le Pen's analysis too, with her party saying Macron, a millionaire former investment banker is the perfect opponent as they seek to make the election a battle between "patriots" and "globalists".