Political outsider Emmanuel Macron joined the increasingly unpredictable race for France's presidency on Wednesday, vowing to take on "the same men and the same ideas" that dominate national politics.

Macron, a 38-year-old former economy minister, announced as widely expected that he will stand as an independent in next year's vote, backed by his centrist movement "En Marche" ("On the Move").

Never elected and "neither of the left or the right" in his own words, the pro-business and tech-savvy former investment banker is hoping to shake up a race dominated by older, more familiar faces.

"We have entered a new era," Macron declared Wednesday, referring to a crisis for Western democracies as well as the dangers of global warming and growing inequality.

"We can't respond with the same men and the same ideas," he added at a news conference held symbolically at a jobs training centre in a gritty Parisian suburb.

The centre-right Republicans party is tipped to win the two-stage election in April and May.

But some analysts are questioning such assumptions after Donald Trump's stunning upset in the United States.

Macron's entry adds another element of uncertainty, with the Republicans and ruling Socialist parties yet to nominate their candidates less than six months before the voting.

The resurgent far-right National Front under leader Marine Le Pen, who announced her slogan "In the name of the people" on Wednesday, is seeking new momentum after Trump's win.

Dismissing Macron as "a candidate of the banks", she said Wednesday that "there is undeniably a new world emerging and there is an old order that is collapsing in on itself."

Her new campaign headquarters are close to the presidential palace on one of Paris' most expensive streets, leading her to joke about having to travel "only 1.7 kilometres" (a mile) to claim power.

- Empty political system -

Macron, who quit the beleaguered Socialist government in August to focus on his own political movement, is expected to steal centrist voters from the Republicans as well as the left.

A poll Tuesday showed him as one of France's most "presidential" figures behind the election favourite Alain Juppe, a 71-year-old former prime minister with one of the longest CVs in French politics.

Juppe is favoured over ex-president Nicolas Sarkozy and former prime minister Francois Fillon for the Republicans' nomination, but polls are tightening ahead of primary voting this Sunday and next.

Macron has a mere two years' experience in government, serving as a sometimes rebellious economy minister from 2014-2016 and as an economic advisor to his one-time mentor, President Francois Hollande.

"I believe that the French people won't put their destiny in the hands of someone with no experience," Fillon said Wednesday.

But Macron believes youth and inexperience are assets in a country weary of a political class blamed for years of low growth, high unemployment and mounting government debt.

"Our political system is blocked," said the high-flying graduate of elite universities who wrote a thesis on Machiavelli, the famously scheming Italian political theorist.

Macron, who quit Hollande's government in August, threw new barbs at his ex-boss on Wednesday.

"I've seen the emptiness of our political system from the inside," he said.

Macron is left-wing on social issues, pledging to bring jobs to deprived areas and a defender of public services, but also pro-business, notably as a vocal critic of France's strict labour laws.

A maverick in politics as well as in his private life, the accomplished pianist is married to his former schoolteacher, a divorcee with three children who is some 20 years his senior.

- Unpopular president -

President Hollande, who has yet to announce whether he will run in next year's election, is reportedly furious at what he sees as betrayal by his one-time protege.

The president called Tuesday for "cohesion" and "uniting" in the divided Socialist party.

Hollande is one of the most unpopular presidents since World War II after a five-year term marked by multiple terror attacks, stubbornly high unemployment and U-turns on key policies.

He was widely panned, even by his own prime minister, after agreeing to collaborate for a tell-all book published in October in which he criticised ministers, judges and the national football team.

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