Bayrou the Kingmaker in French Elections

As soon as they had emerged as the winners of the first round in the French presidential election, Nicolas Sarkozy and Ségolène Royal started courting the centrist vote.

No surprise there, as the 7 million people who backed the third-placed François Bayrou, who took 18.5% of the vote, represent the richest potential pickings for the two frontrunners in the second round on May 6.

In his victory speech Mr Sarkozy, the plain-speaking former interior minister who had talked of a desire for a "rupture", softened his tone. He would, he told his supporters, protect those "in fear of their future", who felt "fragile and vulnerable".

Ms Royal, who trumpeted her nationalist credentials during the campaign by praising the Marseillaise, reiterated her desire to change France without carrying out the kind of painful reforms implied in the Sarkozy approach.

Mr Bayrou - whose "third way" approach was finally found wanting - must now decide whom to back in the run-off. In the final days of the campaign, Mr Bayrou tacked to the left in an effort to pick up votes from the weaker of the two frontrunners.

However, he also took an increasingly antagonistic line towards Mr Sarkozy, whom he criticised for using the word racaille ("rabble") to describe rioters in 2005. So it is hard to see Mr Bayrou making a 180-degree turn in Mr Sarkozy's favour.

But his support for Ms Royal is far from a given: Mr Bayrou clings tenaciously to the idea that what ails France is the country's polarisation and the marginalisation of the centre parties. (Mr Bayrou's UDF holds only 27 seats in the France's 577-seat parliament.) With parliamentary elections due in June, to openly support Ms Royal could undercut his ultimate ambition of rebuilding a centre party.

In the absence of an explicit endorsement from Mr Bayou, the votes of his supporters will be up for grabs. So the second round will see both Mr Sarkozy and Ms Royal tailoring their messages to this group. Indeed, they have already started doing so.

The combined left vote in the first round came to 36.4%, including Ms Royal's 25.84% and that of the other candidates on the left such as the anti-globalisation candidate José Bové and Arlette Laguiller, the Trotskyist candidate. All those on the left can be expected to rally to Royal in a "stop Sarkozy" coalition.

But Mr Sarkozy still has the numerical advantage. The combined left vote does not match up to that on the right. Mr Sarkozy came top, with 31.1%. And the vote for Jean-Marie Le Pen, the founder of the National Front, collapsed to 10.5% from his shock 18% in the first round of the 2002 presidential vote, with many defecting to Mr Sarkozy. Mr Le Pen has said he gets on better with Mr Sarkozy than with Mr Chirac, so it is likely that the 78-year-old former paratrooper will fall in line behind Mr Sarkozy.

So for the second round, Mr Sarkozy can count on a solid foundation of 41% of the popular vote. That makes him the man to beat. But there remain all those Bayrou voters to play for. If - and it is, admittedly, a big if - most of them throw their support for Ms Royal, then she could still pip Mr Sarkozy.

Much will depend on the televised debate on May 2 between Ms Royal and Mr Sarkozy. Both will be making a big pitch for the potentially decisive Bayrou vote.