PARIS — Saying that he wanted to tell the truth to the French people, President Nicolas Sarkozy said Thursday night that Europe could be “swept away” by the euro crisis if it does not change. He said that Europe would “have to make crucial choices in the next few weeks,” and that France and Germany together were supporting a new treaty to tighten fiscal discipline and promote economic convergence in the euro zone.

The European Union needs “an overhaul,” Mr. Sarkozy said, to remain relevant and competitive, but he was vague about the details of what needs to be done. “If Europe does not change quickly enough, global history will be written without Europe,” he said. “Europe needs more solidarity and that means more discipline.”

His televised speech came against a backdrop of deepening alarm about the contagious nature of the euro crisis, which threatens Italy and has begun to sap confidence in France and Germany, the strongest economies among the 17 European Union countries that use the single currency. The crisis has exposed the seeming inability of European leaders to resolve the onerous debt problems of its weaker members, calling into question the survival of the euro, once seen as a glue that would bind Europe together.

Chancellor Angela Merkel of Germany is scheduled to give a similar address to Germans on Friday, but it was clear that Paris and Berlin do not agree on all aspects of a proposal. Mr. Sarkozy said the two would meet on Monday in Paris, before a European Union summit meeting next Thursday and Friday.