On 20 March, with a serial killer still at large, President Nicolas Sarkozy addressed a group of children at a middle school in Paris and did what he does best: frightened them. "Those children are exactly like you," he told his audience, the day after a then-unknown assailant shot dead pupils between the ages of three and eight at a Jewish school in Toulouse. "That could have happened here."
After months of an election campaign in which the president has struggled to defend his role in the economic crisis, Mohamed Merah's attacks on soldiers, schoolchildren and parents enabled Sarkozy to play his favoured role of protector once again.
As interior minister, he built a reputation for tough pronouncements on law and order - notoriously in 2005 when he described urban rioters as racaille, "scum", to be washed off the streets. In 2007, he won the presidency with an appeal to voters that the philosopher Alain Badiou, a staunch critic, characterised as "fear of foreigners, workers, youth from the banlieue, Muslims, black Africans". Now, despite condemning his opponents for their "undignified" politicking over the Toulouse killings, Sarkozy has been doing the rounds of the media, promising new measures such as jail for people who browse terrorist websites and deportation of radical Muslim preachers.
In line with this spin, Sarkozy has stressed that the killer, a French citizen of Algerian extraction who claimed allegiance to al-Qaeda, had nothing to do with Islam and that people should not take "revenge" on Muslims. Admirable words, had they not come from a man who had just spent months ramping up his anti-"foreigner" rhetoric to compete with his far-right rival Marine Le Pen.
For Le Pen, credited with overhauling the image of the Front National, founded by her father, Jean-Marie, the Toulouse killings provided an opportunity to take an even harder line. Previously she had complemented her xenophobia with an anti-EU economic stance that won praise from such quarters as Britain's Daily Mail (though not quite "bravo pour les chemises noires!"). She has now retreated to familiar ground, railing against "le fascisme vert" ("Islamofascism") and claiming that whole districts of suburban Paris are in the grip of Islamists. "How many Mohamed Merahs," she asked in a speech on 25 March, "are arriving every day in France on boats and planes filled with immigrants?"
Sarkozy and Le Pen have been trying to win over the same group of voters - those who dither over the centre right and something more extreme - and, according to Jocelyn Evans, professor of politics at the University of Salford, which of them benefits most will depend on which narrative these voters choose to believe. "Will they see Toulouse as a crime issue or an immigration issue?" he says. "If immigration, they go to Le Pen. If crime, they'll be more attracted to the Sarkozy line." Yet, despite the alarming messages, neither candidate may see much benefit. Le Pen's renewed vigour will "stem the flow" of voters to Sarkozy, Evans says, but won't win her any new supporters. Her chances of making it to the presidential run-off, he suggests, are "vanishingly small".
Meanwhile, Sarkozy faces criticism over the revelation that French security services had been tracking Merah but apparently had no idea of his plans. It rather undermines his claim to be tough on crime.
Stuck in the middle
The most recent opinion polls show that Sarkozy continues to narrow the lead of his Socialist rival, François Hollande, a trend in progress well before Toulouse. Both are hovering around 28 per cent. Hollande's strategy is to behave like a president-in-waiting, avoid being seen to make capital out of the killings (he has minions in the Parti Socialiste who can do this on his behalf) and cruise to victory on a wave of anti-Sarkozy sentiment.
Yet this may not be enough, says Philippe Marlière, professor of European politics at University College London. Many voters are disappointed by Hollande's "centrist" campaign: "The risk is that he's seen as too moderate and not saying much one way or the other." Lionel Jospin, the PS candidate who was beaten to the second round by Le Pen, Sr in 2002, made just such a mistake.
Now a challenge is coming from the other end of the spectrum. After the murders in Toulouse, one candidate stubbornly refused to suspend his campaign. He continued to advocate taxes on the rich, nationalisation of industry and "solidarity" with austerity-battered Greece. He is Jean-Luc Mélenchon, a candidate for the Front de Gauche coalition of Communists and left-wing socialists. He has eaten into Hollande's support and now rivals Le Pen for third place.
Despite the horrors of Toulouse, and the best efforts of right-wing candidates to divert their attention, French voters may still be saying: "C'est l'économie, stupid."
Daniel Trilling's "Bloody Nasty People: the Rise of Britain's Far Right" will be published by Verso in the autumn