Militant French farmer Jose Bove says he wants to stand in the presidential election being held in April and May.
Mr Bove says he wants to speak for those who "have no voice"
An anti-globalisation champion, he was at the forefront of the "No" campaign in the EU referendum held in 2005.
Would-be candidates have until 16 March to gather 500 signatures from mayors to be able to run in the election.
Mr Bove, who has received the sponsorship of some 100 elected officials, says he may struggle to get all 500 required.
The activist, who has also conducted a high-profile campaign against GM crops, told a Paris news conference he wanted to be a "spokesman for those who have no voice".
"We want to say that an alternative is possible, for those who no longer believe in the traditional left," he said, calling for voters to rally behind him to "defeat the right and the far-right".
"I am not the candidate of a party, I am not a professional politician," he said.
"My candidacy is that of a gathering of forces and citizens, from the social, trade union, political and pro-immigration movements, who want a union of their kind of left."
He has been sent to prison three times, most famously for destroying a McDonald's restaurant which was being built in his hometown of Millau, southern France, in 1999, and for destroying GM crops in 2001 and 2003.
Mr Bove is set to find out over the next few days about a judgement from the high court of appeal on whether he faces four months in prison for destroying more GM crops in 2005.
Jean-Marie Le Pen
He has said he will campaign from his cell if necessary.
So far, around 20 people have said they will stand for the presidency, including Interior Minister Nicolas Sarkozy and socialist candidate Segolene Royal - the two most popular candidates according to recent polls.
French President Jacques Chirac has yet to declare whether he will stand.
The first round of the presidential election is due to be held on 22 April.