Paris - Just five years ago a Socialist president, Francois Hollande, was running France. Now supporters are wondering if the left will be more than a footnote in the coming presidential fight.

With under 100 days to go before the vote, the country's multiple leftwing parties are facing near-certain elimination in the first round -- unless they heed calls to unify behind a single candidate.

Polls consistently show that only the far-left pugilist Jean-Luc Melenchon, who scored 20 percent in the first round five years ago, is likely to surpass 10 percent this time.

The others are stuck in the single digits, making it unlikely that any leftist challenger will trouble Emmanuel Macron as he seeks a second term.

It's a stunning reversal of fortune in particular for the Socialists, whose candidate, Paris Mayor Anne Hidalgo, is floundering in the polls.

The candidates seeking to unseat Emmanuel Macron

That has prompted her to urge Melenchon, the Greens candidate Yannick Jadot, the Communists and others to join forces, all of whom have spurned the idea.

In the meantime, former Socialist minister Christiane Taubira, a respected figure among the party's base, has said she is "considering" joining the fray in a unification bid -- further scrambling the chessboard.

Most left-wing voters appear resigned to the fact that 2022 won't be the year the left recovers, even though deteriorating spending power, inequality and the threats from climate change routinely score high as key election issues in polls.

"The left is paying the price for not being capable of sitting down to discuss and build a common project," said Clemence Dolle, a member of the Young Ecologists movement supporting the Greens.

"But we should have done it two years ago -- it's too late."

- 'Don't want to wait' -

For Gerard Grunberg, a veteran political scientist, "it's a disaster. The left has never been this divided since the beginning of the Fifth Republic" inaugurated by Charles de Gaulle in 1958.

Alongside the three largest leftist groups are a half-dozen niche parties, few of which are enthusiastic for a People's Primary planned for end-January by activists hoping to mount a serious challenge to the right by choosing a single candidate.

Adding up all the intentions to vote, leftwing candidates would obtain a maximum of some 30 percent in the first round, according to polls.

"We're here to remind these parties that their job is to respond to the urgent issues at stake," said Mathilde Imer, a spokeswoman for the People's Primary initiative that has garnered over 300,000 signatures.

She said voters "don't want to wait five more years" for the left to put forward a convincing campaign to tackle social and climate issues.

However, "most leftwing parties feel it's already a lost cause, and are choosing to defend their own flags," said Remi Lefebvre, a political scientist at the University of Lille.

Yet even though immigration and security fears are dominating the debate, Lefebvre said France's political centre of gravity has not shifted permanently to the right.

"There is an electoral potential for the left but they aren't able to harness it," he said, pointing to a "credibility problem -- the left's messages are hard to sell and defend."

Calls to step up the global warming fight, for example, are widely perceived as requiring sacrifices that would hurt jobs and growth -- not exactly a vote-winner.

"A good image does not translate into electoral capital when the debate is focussed on security and immigration, issues on which the left is totally absent," said the political analyst Stephane Rozes.

That makes forging a common front all the more urgent if the left wants to recover after the April election.

"I think the left will survive -- as a young activist, you realise that it's the oldest people in the parties that are resisting a joint discussion the most," said Dolle.

By Joseph Schmid and Lea Nkamleun Fosso