Israel's former ambassador to France has expressed his dismay at support given by French Jews to Marine Le Pen, leader of the Front National (FN).
Ms Le Pen won almost one in 5 votes in Sunday's first round presidential election.
Danny Shek, who served in Paris from 2006 until last year, says that there is an increasing view among some Jews that Ms Le Pen is "cleaning house" and should be supported.
Mr Shek said: "What worries me as a Jew and as an Israeli is that more and more Jews find her appealing. There is a growing popularity for the primitive formula, 'my enemy's enemy is my friend'.
"I wrote an article on the French elections for an Israeli newspaper, in which I said this, and I had 250 talkbacks. A good 70 - 80 per cent of them said I was a fool, picking up on this idea. They thought Le Pen was someone who was cleaning house.
"The fact that one in five French voters felt comfortable enough with a party that stands for xenophobia and antisemism is horrific."
France has the biggest Jewish community in Europe, numbering more than half a million.
Richard Pasquier, the president of Crif (the French equivalent of the Board of Deputies) says he is relaxed about the FN. There are antisemites in the party "but they are not the majority...The antisemitism is no longer a main characteristic of the FN".
His predecessor as president, Theo Klein, was similarly unconcerned: "She represents a generation totally different from her father's, who built the FN out of extreme right-wing neo-fascism and nostalgia for the Vichy regime. Of course, I cannot take it for granted that her ideas are different from those of her father, but to regard as fascists all those who voted for her would be a mistake."
But despite Ms Le Pen's PR strategy of cleaning up her party's antisemitic image, the Front National continues to work closely with Frederic Chatillon, a fervent supporter of Hizbollah and promoter of Holocaust-denying literature.
Mr Chatillon, a friend and confidant of Ms Le Pen dating back to their time together at law school, works as her unofficial public relations adviser and provides PR services to the Front National through his media company, Riwal.
Mr Chatillon also runs the Syria news website Infosyrie, which backs President Bashar al Assad. In March 2011, Mr Chatillon wrote: "Dear President Assad, it's the Zionist lobby that the French press orders to destabilise your wonderful country."
In 2006, Mr Chatillon met Hizbollah leaders in Lebanon, accompanied by antisemitic French "comedian" Dieudonné.
But speaking exclusively to the JC, Ms Le Pen defended Iran's nuclear programme and warned that an attack on the country would be a "violation of international law".
She said: "As far as I know, Iran's nuclear effort is defensive, not offensive."
The party leader, whose father and FN founder, Jean-Marie Le Pen, is a well-known Holocaust-denier, insisted: "There is no proof today that the Iranians have any other purpose than a civil nuclear programme and, even if that were not the case, they won't be the first to use the bomb."
But other leaders of French Jewry are extremely concerned by the Front National's electoral success.
Serge Cwajgenbaum, secretary general of the Paris-based European Jewish Congress, said: "It's a worrying time for democracy in France. Jews should of course be concerned first and foremost as French citizens. Marine le Pen has not officially expressed antisemitic remarks, but even if the words have changed, the music remains the same.
"She expects to gain from the general election after the presidential elections. She will try to get as many MPs as possible into the new parliament and she is even referring to herself as the official head of the opposition. She is trying to become the French Gianfranco Fini. She wants to turn her party from extremist to respectable.
Mr Cwajgenbaum added: "Are French Jews nervous? Yes, absolutely. The future is uncertain and this environment is never good for minorities, and especially for Jews."
Benjamin Abtan, the president of the Brussels-based European Grassroots Anti-Racist Movement, said: "The party is as antisemitic as it used to be… Le Pen has a new speech and a new face but the reality is still the same."
As part of her effort to give the Front National an image-makeover, Ms Le Pen declared Nazism an "abomination" while campaigning to lead the party in 2010.
Her party has also claimed that it is "friends" with Israel and, in November last year, Ms Le Pen was photographed meeting Israeli UN envoy Ron Prosor at the UN headquarters in New York.
Many commentators, however, have seen her attempts to build bridges with Israel and the Jewish community merely as part of a wider strategy to oppose the Muslims in Europe.
Evidence of this came in February this year when Ms Le Pen hit out at Parisian supermarkets for, as she claimed, selling only meat from animals slaughtered without pre-stunning.
The statement, which targeted kosher slaughter as much as halal, prompted a wave of rhetoric that terrified Jewish groups in France.
Two weeks later while on the campaign trail, President Nicolas Sarkozy declared that "meat should be labelled according to the way the animal is slaughtered".
Mr Prasquier said the attack in Toulouse last month in which a jihadist shot four people at a Jewish school was one of the factors that pushed many voters towards the National Front because it vindicated Ms Le Pen's campaign against radical Islam.
Gideon Kouts contributed to this report