For almost four decades, Muslims have been the fastest-growing segment of the population in Western Europe. As a consequence, the Muslim vote is becoming ever more important. This first became apparent in the September 2002 general elections in Germany, when Socialist candidate Gerhard Schroeder beat Conservative opponent Edmund Stoiber with the slightest of margins — barely 8,864 votes. Germany is home to almost 700,000 Turkish-German voters — in addition to nearly 3 million non- (or rather not-yet-) voting Turkish immigrants. The Muslims voted overwhelmingly for Mr. Schroeder.

They did so again in 2005, though then the native, or “German-German,” vote went to the right to such an extent that it resulted in a narrow victory for Christian-Democrat candidate Angela Merkel. As time goes by, however, it will become ever more difficult to counter the Muslim voting bloc.

Last year the Muslim vote tipped the balance toward the left in the local elections in both the Netherlands and Belgium. The Institute for Migration and Ethnic Studies of the University of Amsterdam found that 84 percent of the Turkish immigrants in the Netherlands voted for the left, as did 90 percent of the Moroccans. In Antwerp, Belgium’s largest port, the anti-Islamist Vlaams Belang party won 33.5 percent in October’s local elections. Sociologist Jan Hertogen calculated that without the immigrant vote the VB would have polled 40.4 percent and would have beaten the Socialists.

Most of the immigrants who came to Europe during the past decades were attracted by the generous welfare benefits that Western Europe lavishly bestows on the “underprivileged.” Today, as more and more young Muslims reach voting age, European parties have begun to cater to Islamist causes. Left-wing politicians in Europe introduce separate swimming hours for women in public pools, impose halal food on cafeterias and demand that schools banish the Holocaust from history lessons.

Pundits who predict that Western Europe is about to witness a shift to the anti-immigrant right are mistaken. This trend will be over by the end of the decade, when the impact of the immigrant vote will move European politics dramatically to the left. The right’s chances of winning elections are dwindling. The anti-immigrant right realizes this. As Filip Dewinter, the Antwerp VB leader, said after last year’s elections: “I am a realist. The number of potential voters for our party is declining year by year… In the past ten years the number of new Belgians in Antwerp — half of whom are Moroccans — has doubled. … If the number of foreigners in Antwerp continues to grow by 1.5 percent a year, as it currently does, then in 20 years from now there will be more people of foreign than of indigenous extraction in this city.”

The Muslim vote is also bound to have a major impact on the upcoming French presidential elections on April 22. More than 10 percent of the French electorate is Muslim. Since Muslims are the youngest part of the population, representing almost a quarter of those under 20 years of age, their political importance will only grow. In some French cities already half the inhabitants are Muslims. This makes it all but impossible for the right to win in urban constituencies — unless virtually all the indigenous “French-French” cast a right-wing vote.

Nicolas Sarkozy, the candidate of the ruling center-right UMP party, seems convinced that many indigenous French might, indeed, do this. Hence, he is speaking out loudly against an Islamist takeover of French urban neighborhoods, such as the Parisian suburbs. If Mr. Sarkozy’s strategy proves to be the right one, it shows that many French have come to realize that these elections offer the last chance to preserve something of the old France.

Some politicians on the European far-right, however, seem convinced that the Islamization of Western Europe has become inevitable. Like the parties of the left, they hope to counter electoral decline by striking a deal with the Islamists. This explains why last week Jean-Marie Le Pen, the leader of the anti-immigrant National Front in France, emphasized that, unlike Mr. Sarkozy, he does not want to “clean the suburbs out with a high pressure hose.” Mr. Le Pen told the Muslim youths in the suburbs: “You are the branches of the French tree. You are as French as can be.”

We are on the eve of a crackup of the so-called European far right between pro-Islamists and anti-Islamists. This rift was one of the reasons why the Austrian Freedom Party fell apart. Within the French NF, too, traditionalist Catholics feel less and less at ease with the pro-Arab policies of those who consider America to be a greater threat to Europe than North Africa and who prefer Hamas over Israel. One might argue that anti-Semitism is at play here. But it might also be just the same political opportunism that has affected the left.