Nicolas Sarkozy's re-election bid has become tougher after he failed to land a much-needed knockout blow on Socialist frontrunner Francois Hollande in a bitter televised debate.
Wednesday's debate was ferocious, with many French commentators surprised at Hollande's combativeness, with allies of Sarkozy - called hyperactive and aggressive in the past - now accusing Hollande of the same.
Sarkozy had been expected to dominate the sole debate, but instead Hollande shed his image of a soft, consensus builder to repeatedly attack the incumbent, countering his critics and improving his presidential stature ahead of Sunday's run-off.
Sarkozy himself said on Thursday that "an election has never been so uncertain" and the run-off "is going to be very close".
"I thought it would be bitter and it was ... but the debate was about my proposals," said Hollande, who on Wednesday repeatedly preceded his policy proposals with "I, as president..."
Newspaper editorials agreed that the debate "would not bring about an electoral earthquake", with Hollande predicted to win Sunday's run-off with 53-54 per cent of votes, according to opinion polls.
With the right-wing incumbent having trailed in opinion polls for more than six months, Sarkozy several times calls Hollande a "liar" and "arrogant".
Hollande's response was just as fierce and sometimes mocking, accusing Sarkozy of refusing to take responsibility for his record and accusing him of self-satisfaction in a period of grim economic crisis for many voters.
A total of 17.79 million people watched the almost three-hour duel, said audience monitor Mediametrie, down on the 20.4 million who watched Hollande's former partner, Socialist Segolene Royal, take on Sarkozy in 2007.
"We can talk of a draw. But given that Hollande started from a position of favourite, we can also say he remains the favourite," Franoise Fressoz wrote in an editorial in Le Monde newspaper.
Les Echos financial daily took a similar view.
"Neither candidate was in difficulty, but neither definitively gained the advantage either," according to Les Echos, pointing to a "draw, which if confirmed, would favour the favourite".
Sarkozy set out to portray Hollande, who has never held a ministerial post, of being unequal to the task of running the world's fifth largest economy at a time of crisis.
"We are in a dangerous world, a difficult world, where you have to be able to take a decision," Sarkozy said.
"Your normalcy is not equal to the challenges," he told Hollande, referring to Hollande's promise to be a "normal" antithesis to Sarkozy's impulsiveness.
Hollande turned his consensus-making style into a plus, accusing Sarkozy of dividing the French and listing 16 ways in which he would be different.
"Me, as president of the republic, I will never call my prime minister a collaborator ... Me, as president of the republic, I will ensure that my behaviour is always exemplary," he said.
Hollande also took Sarkozy to task over the economy, demanding he take responsibility for unemployment of 10 per cent and a public debt of 1.7 trillion euros ($A2.18 trillion).
Sarkozy blamed the economic crisis and said the reforms he had enacted had saved France from going the route of Greece or a Spain.
"With you, it's simple, it's never your fault," Hollande said, accusing Sarkozy of having protected the privileged.
"You want fewer rich people, I want fewer poor people," Sarkozy retorted.
The two also clashed on Hollande's proposals to reduce the share of nuclear power in the energy mix, his call for eurobonds and his proposal to give foreign residents the right to vote in local elections - all of which Sarkozy opposes.
The pro-Sarkozy Le Figaro had a surprisingly neutral headline - "High tension" - although an editorial laid into Hollande's roots in a left-wing that is better at "speaking about its past than imagining the future".
"Hollande had the advantage of never having exercised power. An enormous advantage when taking on a president whose time in office has been marked by an unprecedented financial crisis," wrote Paul-Henri du Limbert.
The left-leaning Liberation daily headlined "Hollande presides over the debate", with an editorial noting that the two men "clearly wanted a fight".
"The damaging, violent political climate of the end of this campaign also reigned in the dark studio hosting the debate," wrote Nicolas Demorand.
Le Figaro was the only newspaper still predicting a possible Sarkozy victory against Hollande with his "dated language and a disparate left".
Interior Minister Claude Gueant, a close aide to Sarkozy, said that Hollande was "full of arrogance, full of self-importance" while also admitting that he had been "very pugnacious" during the debate.
The head of Sarkozy's UMP party, Francois Cope, said that voters would "shuffle the deck" between the two rounds.
"Sarkozy pushed Hollande ever further back, to the point that Hollande stumbled, which he immediately made up for with a certain aggression," said Cope.
Two days before campaigning ends on Friday night, the run-off candidates are on Thursday to hold rallies on friendly territory: Toulon in the southeast for Sarkozy and Toulouse in the southwest for Hollande.
Centrist presidential candidate Francois Bayrou, who won 3.3 million votes in the first round, is to say on Thursday what his position is, having said he was waiting for the head-on debate before "taking his responsibilities".