Far-right leader Marine Le Pen has vowed to cast a blank vote in Sunday’s French presidential poll run-off.
Marine Le Pen told a rally of her National Front party that she could back neither incumbent Nicolas Sarkozy nor Socialist Francois Hollande and told supporters to follow their conscience.
Marine Le Pen won 6.5 million votes – 17.9% – in the first round of the election.
The latest opinion polls suggest Francois Hollande has a six to 10 point lead over President Sarkozy.
Francois Hollande and Nicolas Sarkozy will go head-to-head in the sole televised election debate on Wednesday.
On Tuesday, Marine Le Pen led her National Front party’s annual rally to its climax at the Place de l’Opera in the French capital.
Marine Le Pen was addressing supporters after winning a record number of votes for her party in the first round of the presidential election and after taking over from her father, Jean-Marie Le Pen, just over a year ago.
“On Sunday, I will vote blank,” she told the rally.
“I have made my choice. Each of you will make yours.”
Marine Le Pen praised the campaign her party had run, saying it had touched the spirit of the French people.
“We have become the centre of gravity for French politics,” she said.
Marine Le Pen said a “great project of emancipation” had begun and nothing would be the same again.
She rounded on both Francois Hollande and Nicolas Sarkozy.
Marine Le Pen said Nicolas Sarkozy’s recent policy switches had contradicted his actions over his five-year term and he was not fit to be president.
Opinion polls suggest about 50% of National Front voters will back the president, about 30% will abstain and about 15% will support Francois Hollande.
Nicolas Sarkozy is holding a large rally on Tuesday in Trocadero Square, Paris, which he says is a showcase of “real work”.
This has irritated unions as it carries the implication that Left-wing unions – who are holding their own May Day rally – do not understand the value of work.
Meanwhile, Francois Hollande told supporters in the central town of Nevers: “French people want change.”
He added that now he was no longer the candidate of the Socialist Party but the candidate of “the whole united Left”.
After the first round on 22 April, far-left candidate Jean-Luc Melenchon – who polled 11% of the vote – told his supporters to rally behind Francois Hollande in the second round.
Francois Hollande has chosen not to attend the unions’ rally at the Bastille, which will be addressed by Socialist Party secretary Martine Aubry.
Large numbers of workers and union members are marking May Day with marches and rallies across the country.
Nicolas Sarkozy continued to court far-right voters on Tuesday in an interview on the RMC radio station, saying France had too many immigrants.
He said: “Our system of integration doesn’t work. Why? Because before we were able to integrate those who were received on our territory, others arrived. Having taken in too many people, we paralyzed our system of integration.”