Paris (AFP) - What if Marine Le Pen wins in May?

Two weeks before the French cast their first presidential ballots, the spectre of victory for the far-right leader who promises to crack down on immigration and outlaw gay marriage sends shivers down many a spine.

Pollsters say the anti-EU firebrand can count on the unwavering support of about one in four voters to get her past the first round of voting on April 23.

Although they also say the National Front (FN) leader cannot win in the decisive May 7 runoff whoever she faces, a great many pundits were wrong about Brexit and Donald Trump after failing to feel the populist pulse.

And with one in three voters still undecided at this late stage, pollsters would be wise to hedge their bets.

Predictions of a "nightmare" Le Pen presidency abound in bookstores and the media.

The 48-year-old candidate poses a "genuine peril", according to Matthieu Croissandeau, editor-in-chief of the left-leaning newsweekly L'Obs, which ran a special report last month titled "Black Scenario of the First 100 Days".

Dozens of actors, singers and other artists put their names to an op-ed in the Liberation daily last Sunday warning: "The National Front is on the threshold of power. We call for a bulwark against Marine Le Pen... in the name of freedom of thought and creativity."

- Exile in Canada? -

Reminiscent of the runup to Trump's election last year, many artists have said they would prefer exile to living under Le Pen. Like Americans virulently opposed to Trump, they say they are looking to Canada as a refuge.

"Just in case, I'm making plans to move to Quebec," leftwing comedian Guy Bedos wrote in a book published in March. "I have an absolute aversion for the Le Pen family," the 82-year-old told AFP.

In 2002, Le Pen's father Jean-Marie Le Pen, now sidelined from the FN because of views even farther to the right than his daughter's, caused a political earthquake in France by winning through to the runoff.

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But in that second round, voters of various political stripes reluctantly joined conservatives to elect Jacques Chirac and block the far right.

Jean-Marie Gustave Le Clezio, the French-Mauritian author who won the Nobel prize for literature in 2008, said as far back as 2015 that he would hand in his French passport if Le Pen becomes president.

Others, including public figures, are promising active resistance to a government led by the far right.

France's ambassador to Japan, Thierry Dana, wrote in an op-ed last month that he would "shelve all diplomatic duties" if Le Pen is elected.

- 'Judges are fighting Trump' -

The foreign ministry had to remind Dana of his obligation to remain neutral over the election.

Also throwing neutrality to the wind was Francois Durpaire, an educator and historian who co-authored a comic book titled "La Presidente" (using the feminine form of the noun) depicting France under Le Pen.

"For me as a professor of education sciences the question I would ask the next day (after a Le Pen victory) is: 'How do you teach in French schools under Le Pen?'" he told AFP.

"I know what to do. I'll stay in France, I'll respect the outcome of the democratic vote, but I will resist with all my might any measure that goes against French law," he said, citing Le Pen's pledge to give French nationals priority access to public services including schools.

Keeping non-citizens out of French schools would be a "red line" for Durpaire.

"We will be able to mount not just moral resistance, but also legal resistance," he said, noting: "Judges are fighting Trump, not just far-left activists."

Trump's efforts to bar entry to nationals of a string of mainly Muslim countries have been blocked by federal courts in several US states.

The head of the International Human Rights Federation, Dimitri Christopoulos, also said he would join the battle against a President Le Pen.

Her victory "would be a political defeat for human rights, but we would continue to fight," he told AFP. "The ideological battle will be an existential priority for our societies," said Christopoulos, a staunch defender of migrants' rights who divides his time between France and Greece.

Laurent Joffrin, editor-in-chief of the leftwing daily Liberation, said resistance should begin with the legislative elections in June that will determine the shape of the future government.

"We won't have fascism on day one," he said. "France has a constitution and institutions, and laws need a majority to pass in parliament. So the immediate fight is to prevent the FN from winning a majority to implement its agenda."

Joffrin also noted that if Le Pen wins, she is unlikely to have enough support outside her party to form a coalition government and would be forced into a co-habitation arrangement.

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