Le Pen's mask slips as he plays the race card against Sarkozy

The candidate who claims to be closest to the people rarely leaves his office, except to go to the radio or TV studio. The candidate who promises never to lie to the electorate refuses to say what he would do if elected.

Jean-Marie Le Pen, 78, is the "invisible man" of the French presidential campaign: invisible but ever-present, like a virus. He began the campaign pretending to be a more mellow, and more tolerant, man. But in his latest broadcast appearance - he seldom appears in public - the veteran far-right leader reverted to his favourite theme: xenophobia.

The front-running, centre-right candidate, Nicolas Sarkozy, "comes from an immigrant background," Mr Le Pen told a radio interviewer on Sunday. By comparison, he, Mr Le Pen, was a candidate of the terroir: literally, a candidate rooted in the native earth.

"It's obvious, there's a difference," Mr Le Pen said. "There is a choice there which might be considered fundamental by a certain number of French people".

This is Jean-Marie Le Pen at his most poisonous and his most plausible - and also his most effective.

Mr Sarkozy, 52, the man who is favourite to be the next President of France, is indeed half-Hungarian and a quarter-jewish on his maternal, French side. He does not look particularly French; his name does not sound French. Ask almost anyone in France if this will make a difference to their choice in the presidential election on 22 April and 6 May and they will say "no". Mr Le Pen knows, however, that it does make a difference, for a significant minority of French people, especially people on the hard right, tempted to vote for Mr Sarkozy.

Mr Le Pen, and he alone, has been prepared to break the taboo and make a public issue of Mr Sarkozy's Hungarian and Jewish blood. When challenged - as he knew he would be - he immediately pointed out that Mr Sarkozy had himself boasted of his immigrant background during the campaign. If Mr Sarkozy had not mentioned his family, Mr Le Pen said, he would not have mentioned it either.

At 78, fighting his fifth - and presumably last - presidential campaign, Mr Le Pen has lost none of his tactical brilliance or his moral cynicism. He knows, better than anyone, how to touch the buttons of inchoate anger and xenophobia.

Although placed fourth by the polls, Mr Le Pen insists that a "tsunami" of "rejection of the system" will carry him into the crucial top two places in the first round on 22 April. Can he repeat his extraordinary coup of 2002 and reach the second round?

Mr Le Pen has been creeping up in the opinion polls, to around 13 or 14 per cent. Last time he knocked out the Socialist prime minister, Lionel Jospin, with just under 17 per cent. There are two candidates ahead of him this year: the unconvincing Socialist, Ségolène Royal, and the likeable but undynamic centrist François Bayrou.

Mr Le Pen predicts that they will cancel one another out, and he will dart between them, with about 20 per cent of the vote, and reach the second round.

There are a number of reasons to believe that Mr Le Pen will fail. First, he has never scored more than 18 per cent in a national election. Second, he is an old man and beginning to look his age. (His decision barely to go on the road is partly strategic but may also be intended to conserve his flagging energy.)

Finally, he has a candidate running against him this time - Mr Sarkozy - who has stolen and moderated many of his favourite issues: immigration, insecurity, excessive taxation and nationalism.

Another shock cannot not be ruled out, however. Mr Le Pen predicts that somewhere around 5 per cent of the 30 per cent of voters now supporting Mr Sarkozy will return to the far right on 22 April. Hence his decision to make Mr Sarkozy's Hungarian - and implicitly his Jewish - blood an election issue.

And there is a further complication. Pollsters in France have never managed accurately to gauge Mr Le Pen's support. Le Pen voters systematically lie. This year his electorate is even harder to plumb than ever.

An unknown but significant minority of far left voters - and even Arab and African - voters say they are tempted to vote Le Pen this time out of bloody-mindedness, frustration or determination to "make the system explode". Last fling or not, Mr Le Pen may have one shot left in his locker.

Independent