Polls point to the likelihood that French voters will shake the continent on Sunday by rejecting the European Union's landmark constitution, planned as the next major step in a 50-year process of bringing together nations once divided by wars and mistrust.
The latest opinion survey released by Le Figaro newspaper and Europe 1 radio suggested that 55% would vote 'no' to the treaty, with 45% saying 'yes'.
On Friday, the last day campaigning is allowed before the vote, German Chancellor Gerhard Schroeder and Spanish Prime Minister Jose Luis Rodriguez Zapatero planned to lend their support to French rallies for the 'yes' camp.
About 42 million people are registered to vote. Polling begins in France's overseas territories on Saturday, with voting on the mainland a day later.
A 'no' vote could, at least temporarily, kill off the treaty and its stated goal of closer European integration.
Proponents say the constitution will streamline EU operations and decision-making and give the bloc a president and foreign minister. But French opponents fear it will lead to a loss of sovereignty and an influx of cheap labour.
"On Sunday, each of us will have a part of France's destiny in their hands"
On Thursday, President Jacques Chirac made a solemn, last-ditch effort on television to convince the French to vote 'yes'.
"On Sunday, each of us will have a part of France's destiny in their hands," he said. "What a responsibility if France, a founder nation of Europe, took the risk of breaking the union of our continent."
By boosting French voting power in European Union decisions, the treaty will help France "defend its interests and remain one of the motors of Europe," he said.
But a French rejection would be regarded by other Europeans as "a no to Europe".
Chirac urged the French not to turn the polling into a vote of sanction against his government.
"We must not mistake the question," said Chirac. "It is not about saying yes or no to the government. It is about your future, that of your children, of the future of France and the future of Europe."
If 'no' wins, Chirac would suffer the humiliation of becoming only the second leader, after General Charles de Gaulle, to lose a referendum since the founding of the French Fifth Republic in 1958.
The president has said he will not resign if the French vote 'no'.
But government officials said he would likely replace his faithful but unpopular right-hand man, Jean-Pierre Raffarin, who in three years as prime minister has overseen a rise in the unemployment rate to 10% and difficult reforms to pensions, health care and other treasured French social protections.