Spanish Prime Minister Jose Luis Rodriguez Zapatero defended European integration before the French parliament, 10 days after Spanish voters approved the new European constitution.  But Lisa Bryant reports from Paris that the charter faces a more uncertain future in France.

It is not every day that a Spanish leader appears before the French National Assembly in Paris.  But Mr. Zapateros impassioned defense of Europe and of Spanish-French relations had a special motive: to promote the new European constitution, which must be ratified by all 25-member nations to go into effect.

Describing himself as a convinced European, Mr. Zapatero said Europe symbolized a great hope for peace and a medium to fight against the injustices of the world.

Despite a low turnout last month, Spanish voters overwhelmingly approved the new charter in Europe's first referendum.  Three other E.U. countries have approved the constitution by parliamentary vote.

A closely-watched campaign on the charter is now beginning in France.  In theory, a single EU country voting against the constitution could scuttle it.  In practice, some analysts believe a political solution could be worked out.  But that may be more difficult when it comes to powerful EU members like France, a founder of the European block.

Monday, French lawmakers passed a constitutional amendment that clears the way for a referendum on the charter.  The referendum is expected to take place before the end of June, but French President Jacques Chirac has not set a date.

Many ordinary French are far from enthusiastic about the constitution.  Some fear France's national identity is being undermined by a larger and more powerful Europe.  Others, including trade-union activists, argue the constitution erodes social and economic rights.

Still others tie the constitution to the separate issue of Turkey's possible EU membership, which many French oppose.  While a new public-opinion poll published by the CSA agency found 63 percent of French say they would vote in favor of the constitution, previous surveys have found waning support for it.

A number of French politicians are also at odds over the constitution, including a large minority block of the opposition Socialist party.