French men and women voted in a referendum to reject the European Union's first constitution -- a document drawn up by their own former President Valery Giscard D'Estaing, after long consolations with other EU member states.
Senior analyst Dick Leurdyk at the Netherlands Institute of International Relations says the debate on building Europe is changed for ever.
"We are now in a new political environment, the discussion on Europe will never be the same as it was before yesterday, the European unification process until that moment was mainly a process for the political elites in Europe," Leurdyk says.
Now, he says, the man in the street is involved in the modalities of EU integration and for that reason, any discussion on the future of the European unification process will have a different, more democratic flavour.
The constitution faces another referendum in the Netherlands on 1 June, and it appears that it could fail there also. The French "no" has been motivated by a number of factors, including fears that the constitution would damage the French social security system.
But Leurdyk says the EU's rate of expansion to the east has been too rapid for the French to accept, especially in view of the fact that a host of other countries are lining up for membership, including Ukraine, Moldova, the western Balkan countries, and Turkey.
"One of the big concerns, which has now come to the fore, has been the fact that so many people really are afraid of the speed of the unification process, the fact we now have all of a sudden 10 new members, [the EU has grown] from 15 to 25, that seems to have been one of the main factors for many people [in France] to say no, and this is certainly also the case with the debate we have here in the Netherlands," Leurdyk says.
Another senior analyst, Marius Vahl of the Center for European Policy Studies in Brussels, says French voters appeared particularly concerned about the prospective accession of Turkey. He says it's possible that the opening of accession talks between the EU and Turkey set for 3 October will now be put off.
Another factor complicating Turkey's prospects is the decision of unpopular German Chancellor Gerhard Schroeder to hold early general elections this year. All the signs are that the opposition Christian Democrats will win in Germany -- and they oppose Turkish EU membership. Vahl says the Turks themselves seem to have sensed a change in the atmosphere.
"There has been the impression over the last couple of months also that the Turks are not pushing their reform process so hard any more, though the Turks will vehemently reject that notion," Vahl says.
Vahl says that such a perception, if it continues, could for instance be used by the EU as an excuse to delay the start to Ankara's entry negotiations.
Multiplying Turkey's problems is the recent change made to France's own constitution.
"The French changed their constitution [in March], meaning that any new accession treaty, after Romania and Bulgaria, will now require a referendum in France," Vahl says.
He says this constitutional amendment has been largely overlooked amid the campaigning for yesterday's referendum. Nevertheless, it creates another hurdle to joining the EU, and theoretically at least, could even ensure that the EU never expands again.
But analyst Leurdyk says its necessary not to overdramatise the situation. He says that in the past 50 years the EU has suffered other setbacks.
"It certainly is not the end of the European unification process, there will be a time of reflection, a time of standstill, for the present, but I am sure that the unification process itself will continue after a while," Leurdyk says.
The constitution was meant to streamline the EU's decision-making process to cope with enlargement. But analyst Vahl says the EU can simply go on as before without the new constitution.
"The constitution does not really change that much of the substance of European integration, it codifies a lot of the basic principles, it introduces a couple of new positions which relate to practical arrangements, they don't really mean that much, although it does extend qualified majority voting quite a lot, it does not necessarily provide for much more integration," Vahl says.
Another uncertainty that has been created by the French vote is the impact it will have on the single currency, the euro.
The euro has been riding high for many months, as the U.S. dollar has sunk in response to doubts over American economic indicators. But now the uncertainty over the future course of the EU, plus early German elections, plus the poor performance of the eurozone's major economies, could combine to force down the value of the euro.