She is described as the "favourite" to succeed President Emmanuel Macron.
The French far right plans to rally supporters today after its leader Marine Le Pen was convicted of embezzlement and banned from public office.
The move is likely to rule her out of the 2027 presidential election.
The bombshell court ruling has stunned the French political establishment, with even some of her fiercest opponents saying the far-right leader should be allowed to stand in the 2027 vote. She has filed a complaint.
"People of France, let us mobilise to defend freedom, save democracy and support Marine!" wrote Le Pen's National Rally (CN) party in X ahead of the Paris protest.
Opinion polls suggest that Le Pen, 56, could easily win the first round of the two-round presidential vote if she were to run - the latest poll by polling agency Elabe for broadcaster BFMTV, shows her getting up to 36% of the vote.
She is described as the "favourite" to succeed President Emmanuel Macron.
On March 31, Le Pen was found guilty of embezzlement and given a partial suspended sentence and an immediate ban from holding public office, AFP reported.
Her supporters described the decision as politically motivated, but Macron insisted the French judiciary was "independent".
US President Donald Trump called the verdict a "witch hunt" by "European leftists who use legal means to silence free speech and censor their political opponent".
Prime Minister Francois Bayrou dismissed that remark as "interference" in French affairs, in a newspaper interview published on Saturday.
He added that it was "neither healthy nor desirable" to stage a demonstration against the court's decision, insisting that French institutions allowed for "the separation of powers and the protection of justice." | BGNES