Emmanuel Macron has emerged as undisputed king of the French centre ground, but shifting sentiment and alliances make predicting this year's presidential election as difficult as ever.
Macron, a 39-year-old former economy minister, was given little chance when he launched a new political movement "En Marche" last year ahead of a vote that was billed as a fight between conservatives and the far-right.
But the pro-European progressive is now a frontrunner to become France's next leader and will draw fresh strength from Wednesday's announcement of a potentially vital alliance with veteran centrist Francois Bayrou, who decided against mounting a rival presidential bid.
The two were to meet on Thursday afternoon with Macron hoping the tie-up can boost his chances after a tricky 10 days that have seen him lose momentum just as far-right candidate Marine Le Pen picks up speed.
Bayrou acknowledged that Macron was in a "bit of a difficult spot" on Thursday as he spoke about their alliance aimed at ending the post-war lock on France's politics enjoyed by mainstream parties.
"The feeling he had, I think, was that it was an important moment for him, but not only for him, for changing the political life of France," Bayrou told RTL radio.
Macron's unforeseen rise illustrates the difficulty in forecasting this year's two-stage election on April 23 and May 7 which is being widely watched by governments and investors around the world.
Polls currently show anti-EU far-right leader Le Pen winning the first round with around 25-28 percent of the vote, but losing in the second round where she needs more than 50 percent.
The ultimate winner is therefore currently seen as Macron or Francois Fillon, the long-time favourite and conservative candidate for the right-wing Republicans party.
But the unstable international background -- from Donald Trump and Brexit to the surge of right-wing nationalists in Europe -- is mirrored by an anti-establishment and angry mood in France.
Unpopular Socialist President Francois Hollande decided not to run for re-election in December after a five-year term marked by a series of terror attacks and high unemployment.
Both the Republicans and the Socialist parties overlooked the most obvious candidates when choosing their nominee in primary votes.
And Le Pen and Fillon both face serious legal investigations into their use of allegedly fake parliamentary aides which could have consequences between now and election day.
Fillon was described as "completely lost" by former rightwing president Nicolas Sarkozy after the two men lunched together last week, according to a report in the Canard Enchaine newspaper.
A final election twist, largely overlooked until recently, is the potential for a tie-up between the splintered leftist candidates which would produce another political earthquake.
Polls show that Socialist candidate Benoit Hamon, Communist-backed Jean-Luc Melenchon and environmentalist Yannick Jadot have enough supporters to mount a serious challenge together.
"Benoit Hamon has reached out to Jean-Luc Melenchon, he's even reached out to Yannick Jadot," the spokesman for the Socialist government, Stephane Le Foll, told France 2 television on Thursday.
Le Foll urged Hamon to make a deal quickly, adding: "Personally I'm in favour of alliances."
France's splintered Socialists are still haunted by the 2002 presidential election when their divisions led them to be knocked out in the first round, with far-right leader Jean-Marie Le Pen -- Marine's father -- going through to the run-off.
A leftist alliance would make Macron's route to the presidency more difficult, but he could still -- thanks to Bayrou's decision -- claim to be the only centrist in the race.
His platform -- which critics say is still too vague -- is more pro-business and reform-minded than his leftist rivals who have large tax-and-spend programmes.
He is also instinctively pro-European and is at ease with multiculturalism in France, whereas Fillon and Le Pen have both railed against the threat to French identity posed by Muslims in particular.
But Macron remains inexperienced, having served only two years as an economy minister and the same amount of time as a political advisor to Hollande.
He was forced to backtrack last week during a visit to Algeria where he talked about France's 130-year colonial rule there as a "crime against humanity," leading to fierce attacks from his rightwing rivals.