PARIS — France’s presidential contenders were scrambling Monday to make sense of the magnitude of dark horse François Fillon’s victory in the first round of the conservative Les Républicains' party primary.

While the center Right was contemplating its possible demise, the center Left — so far represented by former Economy Minister Emmanuel Macron — hoped to appeal to voters repulsed by Fillon’s hard-line social and cultural policies.

The Socialists, in disarray, tried to gauge whether Fillon would be an easier foe for President François Hollande, should he decide to run again. And the far-right National Front played up its differences with Fillon, in case its own supporters were tempted to look at him more closely — and more favorably.

In other words, just 1.8 million voters — the number who voted for Fillon — brought serious disruption to a French presidential race that was only beginning to make sense.

The first major victim of Sunday’s stunner was Alain Juppé, the former prime minister who had been favorite until a few days before the vote and was confident in the electorate’s desire for a safe pair of hands. He now faces an uphill battle after Nicolas Sarkozy, conceding defeat, backed Fillon in the second round saying “whatever the differences” they have had, Fillon “understands France’s challenges” better than Juppé.

To clinch the nomination, Fillon needs only to convince a third of Sarkozy’s first-round supporters. A poll published Sunday night saw him winning by 56 percent to Juppé’s 44 percent in next Sunday's playoff.

The Juppé camp affected serenity on Monday. “This can be overcome within a week, it's doable,” said one aide, identifying the weaknesses in Fillon’s platform as his radical plan to overhaul the public sector and enthusiasm for Russian President Vladimir Putin.

The key question is whether people whose motivation for voting on Sunday was to get rid of Sarkozy — as many as 42 percent, according to one poll — will turn out in the second round. “Fillon doesn’t trigger the same tension as Sarkozy did among centrist voters,” said Bruno Jeanbart of polling firm OpinionWay.

Polls estimate that 12 to 15 percent of participants in Sunday's primary were Socialist sympathizers who may believe it is "mission accomplished" now that Sarkozy is out of the race. If they stay away in the second round, that could ensure Fillon an impressive win.

However, it is also possible that the first round's high turnout, with more than 4 million voters in the first-ever primary election for the French Right, will encourage even more people to turn out next Sunday, said Jeanbart.

Status quo, or backwards

Another first round victim of the conservative primary is Macron, the former Hollande cabinet minister courting the same centrist, pro-reform segment of the electorate as Juppé. Like Juppé, he is one of France's most popular politicians but must face up to the fact that popularity means nothing if it doesn't translate into votes, as the centrist space of France's political life seems to be disappearing.

Macron told Le Monde on Monday that the Right’s remaining two candidates presented a choice between “the status quo [Juppé] and going backwards [Fillon]” — a reference to Fillon's conservative stance on social issues such as gay marriage. “Who can these guys turn to now? Certainly not Fillon, who’s an arch-conservative on social matters,” said one Macron adviser.

Macron’s fate, however, will be determined by what happens in the Socialist camp, which had bet on Sarkozy as an easier rival in next year's presidential contest. In a now infamous book of interviews with Le Monde reporters, Hollande had confidently forecast that “Fillon has no chance" in the conservative primary.

Hollande's last sliver of hope is that moderate and left-wing voters will cling to him if the contest shapes up as a duel between the hard Right (Fillon) and far Right (Marine Le Pen).

The Hollande team was attempting on Monday to spin the conservatives' first-round result as proof that polls don't mean much six months before an election. Fillon was polling at around 5 percent in voter intentions for the primaries back in the summer. That's close to the 6 percent of voters who believe Hollande is doing a good job, according to polls.

But the French president must also ponder a stark message: Sarkozy's surprise elimination in the first round gives him another reason to think carefully before running in January's Socialist primary — a decision he must make by December 15. As one Socialist apparatchik put it on Monday: “The largest party in France by far is the party of those who want to send their last two presidents home and forget about them.”

Hollande's last sliver of hope is that moderate and left-wing voters will cling to him if the contest shapes up as a duel between the hard Right (Fillon) and far Right (Marine Le Pen). But the many contenders from the Left already lining up against him make that possibility remote. Outside of the Socialist Party, leftist Jean-Luc Mélenchon is the current poll favorite; inside the party, former Hollande ministers Benoît Hamon and Arnaud Montebourg seem determined to fight him to the end.

Macron, for his part, reiterated Monday his intention not to run in the Socialist primary, but to fight it alone all the way to the election. If Hollande decides not to run, his current prime minister, Manuel Valls, is warming up as substitute, but he is almost as unpopular as the president and like him has little chance of making it past the first round of the election next April.

The final collateral victim of Sunday’s vote may be Marine Le Pen, who remains confident of making it to May's second round. She faces competition from Fillon on her core issues: Islam, immigration and school reforms. So the Front has begun counterattacking against Fillon's economic platform, with deputy FN leader Florian Philippot accusing him of planning “incredible violence” against French workers.

Front leaders are also reminding French voters that Fillon was prime minister for Sarkozy's entire five-year term — which may give the ousted Sarkozy a cameo role in next year's general election.