France, Nov. 9 -- Addressing more than 20,000 supporters at Le Bourget, north of Paris, on Saturday, the 75-year-old leader of the hard-left France Unbowed (LFI) movement rejected calls to soften his message to appeal to a broader electorate.

"Other commentators advise me to water down my message to win people over and be less divisive. I will not do that," he told a predominantly young crowd.

"I have only one sensible thing to propose to you: we must change everything."

The rally showcased LFI's newly published presidential manifesto, L'Avenir en commun - A Shared Future - containing 1,069 proposals ranging from higher taxes on the wealthy and retirement at 60 to lowering the voting age to 16.

Central to his programme is replacing Fr...