Monday as they battled for votes from the undecided center ground that will be key to their May 6 runoff. Sunday's first round ballot set up a classic race between left and right in France after Sarkozy, the conservative former interior minister, scored a resounding win with 31.2 percent against 25.9 percent for the Socialist candidate Royal.
Polls give Sarkozy an edge before the decisive second round, with 52-54 percent support against 46-48 percent for Royal.
But the result had both candidates eyeing supporters of centrist Francois Bayrou, who captured 18.6 percent of the vote after a dynamic campaign based on a pledge to sweep aside the ruling elite and overcome traditional political divides.
"Essentially the results will be dictated by the behavior of his voters. They are the ones who will make a difference," Roland Cayrol, head of pollsters CSA told Le Parisien newspaper.
Bayrou, head of the small center-right UDF party, has not given any endorsement and with polls suggesting his supporters could vote either way, spokesmen for the two candidates looked past the man himself to appeal directly to his voter base.
Socialist party leader Francois Hollande said Royal's team would not be beginning negotiations with Bayrou's camp but he said she would be appealing for as broad a majority as possible.
"There are men and women in Francois Bayrou's electorate who wanted change, who thought they would beat Sarkozy by voting Bayrou," he told France 2 television.
Both candidates resumed campaigning on Monday, with Sarkozy meeting a women's association in Paris before travelling to the eastern city of Dijon for an early evening rally, while Royal goes to Valence in southern France for an open air meeting.
They hold a televised debate on May 2 which is likely to be key to helping undecided voters make up their minds.
"They have to reflect on the question of knowing who has the most experience, the most courage, the strongest will," said Francois Fillon, a close Sarkozy aide who is tipped as a possible prime minister.
Whoever wins will have to address the deep discontent of a country suffering from one of the highest unemployment rates in the European Union and with memories of riots in its deprived multi-ethnic suburbs less than two years ago still raw.
Sarkozy's victory on Sunday owed much to his success in siphoning off support from far-right leader Jean-Marie Le Pen with a campaign based on fighting crime and illegal immigration and encouraging hard work for more pay.
Le Pen himself came fourth on Sunday with 10.44 of the vote -- his worst showing at a presidential election since 1974.
However, Sarkozy made clear that he would swing to the center before May 6 in a bid to soften a combative image that delights his supporters but scares many other voters.
