The shock of the campaign so far has been the Communist-backed Left Front candidate Jean-Luc Melenchon, who has surged to third place in some polls ahead of the first round on April 22nd.
The 60-year-old former Socialist minister and senator has struck a chord with many voters with his virulent attacks on the rich, France's elite and austerity measures.
Backed by a coalition of left-wing parties, Melenchon has seen his support rise from less than 10 percent at the start of the year to between 12.5 and 15 percent in recent polls.
A firebrand speaker who has called for a "citizens' revolution" in the two-round vote, Melenchon has galvanised the left, drawing support away from Hollande just as Sarkozy has surged in voter intentions.
He has drawn large crowds of supporters to public rallies, including tens of thousands in Paris last month for a symbolic march to "retake the Bastille" -- the square where the mediaeval fortress and prison was stormed in the French Revolution.
His rise has stolen some of the spotlight from far-right candidate Marine Le Pen of the National Front (FN), who is making her election debut after having inherited the party leadership from her father, Jean-Marie Le Pen.
The telegenic Le Pen, 43, was hoping to repeat her father's stunning showing in 2002 when he defeated Socialist Lionel Jospin in the first round before losing to Jacques Chirac in the second.
Calling for "economic patriotism" and vowing to leave the eurozone, she has railed against globalisation and the "Islamification" of France, initially gaining some ground with attacks on the production of Islamic halal meat.
But Sarkozy has stolen her thunder on two key issues for the far-right -- immigration and security -- with his calls for fewer immigrants and his handling of last month's attacks by an Islamist extremist in Toulouse.
Recent polls have shown Le Pen with between 13 and 16 percent support.
Centrist Francois Bayrou, 60, gained a surprise 18.5 percent of the presidential vote in 2007 but has been lagging in recent polls.
The head of the Democratic Movement and former teacher is making his third run at the presidency and has campaigned to reduce public spending while maintaining France's "social and republican model".
But recent polls have seen him languishing in fifth place with between 10 and 12.5 percent of the vote. Bayrou will be closely watched ahead of the May 6th second round to see whether he throws his support behind either Sarkozy or Hollande.
Of the five other candidates registered in the race, Green Party contender Eva Joly has seen support of two to three percent in recent polls and the others were all at less than two percent.