By Bruce Stokes, Director of Global Economic Attitudes, Pew Research Center

Special to BBC News

A political, economic and demographic divide has opened up between France and Germany. And, if that were not trouble enough, a new Pew Research Center survey suggests that these two countries, which have for decades been the driving force behind European integration, increasingly see the world through different lenses.

The Franco-German alliance was based on rough equality between these two continental powers. In the 1980s, West Germany’s economy and population were slightly larger than France’s, but not overwhelmingly so, and French economic growth actually exceeded its neighbour’s.

Three decades later, this rough balance between Germany and France no longer exists. Germany’s population is now a quarter larger than that of France, the German economy is 38% bigger. And while the German economy grew at an admittedly weak 0.9% in 2012, the French economy did not grow at all.

The demographic and economic decoupling of Germany and France is now complicated by a widening gap in French and German public opinion – and a convergence of French attitudes with those in southern Europe.

Today the French and the Germans differ so greatly over the challenges facing their economies that they look as if they live on different continents, not within a single European market.

Eight out of 10 French people say unemployment is a very big problem compared with less than three out of 10 Germans. More than two-thirds of the French think inflation is a major issue, less than a third of Germans are similarly worried about rising prices. And 71% of the French are very troubled about public debt. Only 37% of the Germans share such concern.

More important for the future of the European Union, in 2009, 43% of the French were of the view that European economic integration had strengthened the French economy. At the same time, 50% of Germans thought integration had benefited Germany, a seven-percentage-point difference. Today, the figures for France and Germany are 22% and 54% respectively – a difference of a full 32 points.

The French and Germans have also parted ways in their views of the European Union as an institution. In 2007, before the euro crisis, 62% of the French and 68% of the Germans had a favourable opinion of it. In 2013, just 41% of the French still hold the EU in high regard, while 60% of the Germans do. A six-point gap in attitudes has grown to a 19-point gap in just a half dozen years.

These figures suggest that the French are now even more eurosceptic than the British, 26% of whom say European economic integration has strengthened the British economy, and 43% of whom have a favourable opinion of the EU.

Meanwhile, the French think more and more like southern Europeans.

As in France, more than three-quarters of Greeks and Italians believe economic integration has been bad for their country, and more than half of Spanish and Greeks look unfavourably on the EU.

Roughly nine out of 10 French say their economy is doing poorly, as do a similar proportion of Spanish, Italians and Greeks. Two-thirds or more of people in all four countries believe their elected leader has done a bad job handling the economic crisis.

And by all of these indicators French attitudes have worsened dramatically since 2007, much as has sentiment in Spain and Italy.

Roughly one in five French people say they could not afford food, health care or clothing at some point in the past year. And only 11% of the French think their economy will improve over the next 12 months. This makes the French among the most pessimistic of Europeans. Just 9% think their children will be better off financially than their parents, by far the gloomiest forecast for the next generation of the eight countries surveyed.

For the last generation, at least, the Franco-German alliance has been the motor driving every effort to broaden and deepen the European Union. Few observers believe that political union, or even more extensive economic integration, is possible in the absence of strong joint leadership by Paris and Berlin.

This new evidence of a dramatic divergence of public opinion across the Rhine on the problems now facing Europe and the merit of the European Union itself raises new questions about prospects for the European Project.