It was the fact that Jean-Marie Le Pen, a far-right, anti-Semitic, racist candidate peddling a toxic brew of anti-immigrant invective and nostalgia for an authoritarian past, came second in the vote.
Instant telephone surveys suggest Chirac will beat Le Pen in the run-off on May 5 by the greatest landslide ever, as much as 80 percent to 20 percent, in the second round of voting. The extreme right-wing vote has not actually grown. But just how racist is France if around one-fifth of the voters can bring themselves to vote for Le Pen? Indeed, how racist is Europe, where the past few years have seen far-right candidates winning places in coalition governments from Norway to Italy?
In a continent that only half a century ago was over 99 percent white, "race" and immigration are essentially the same issue. The proportion of relatively recent non-European immigrants and their children is now running between 5 and 10 percent of the population in most European countries, so immigration has become a hot-button issue for those who share Le Pen's apocalyptic view that "we risk being submerged."
There used to be an unwritten understanding among mainstream parties in Europe to exclude the fascists and racists from their coalitions. But in the last few years that understanding has broken down in a number of countries.
It fractured most spectacularly in Italy, where Silvio Berlinguer's right-wing Forza Italia party swept to power last June in coalition with the anti-foreigner Northern League and the "post-fascist" National Alliance.
In October, a government propped up by the far-right Progress Party took power in Norway. The same thing happened in Denmark in November, with the ultra-right Danish People's Party entering government, and again in Portugal last month with the inclusion of the anti-immigrant Popular Party in the government.
It may happen next month in the Netherlands, where an upstart anti-immigration party led by a charismatic populist called Pim Fortuyn is forecast to take up to 20 percent of the vote.
But despite what is certainly an anti-immigrant backlash in some countries at the moment, the larger picture is not discouraging. The further east you go in Europe, the more overt the racism gets. But that's because under the communists people had virtually no experience of immigrants until a dozen years ago.
In some small, very homogeneous countries like Austria and Norway, even the slightest shift in perceptions of who "we" are causes a major collective psychological crisis. But in the bigger countries like Britain, France and Germany, the situation is generally not bad at all.
There are ugly exceptions like the northern English mill-towns, where uneducated Pakistani immigrants and the old white working class were left to rot together when the mills closed down. In France, disgruntled whites in declining industrial towns, and in depressed rural areas where jobless North African ex-farm workers live in misery, have been the main source of Le Pen's vote for decades.
Former East Germans blame "foreigners" and "immigrants" for all their post unification hardships.
But the more important truth is that in the big cities where most Europeans live, race relations, especially among the young, are actually pretty good. The neighborhoods aren't segregated, young people intermarry without a second thought - and even if you get mugged by a kid gang in the dreadful wasteland of "HLMs" (low-rent high-rise blocks) that ring most French cities, at least the gang will be multi-racial.
Four out of five French citizens will vote against Le Pen in the run-off next month, even though half of them will have to hold their noses in order to vote for Chirac instead. What Sunday's vote showed was no more than that the French are mightily fed up with being ruled by the same smug and mediocre set of aging politicians.