Corsicans vote Sunday in a closely watched referendum, aimed at giving the troubled Mediterranean island greater self-governance. The French government hopes a "yes" vote could end more than 25 years of separatist violence. The vote promises to be close.

Sunday's referendum in Corsica deals with a number of constitutional changes, including an offer of parity for women in the island's regional assembly. But the most controversial item appears to be a technical one that would collapse Corsica's two administrative departments into one.

The aim is to concentrate local powers on the island and, separatist-minded politicians believe, mark the first step toward greater autonomy that they have sought for years.

For the government of French Prime Minister Jean-Pierre Raffarin, offering the island limited self-rule would be one step toward ending years of bloodshed by Corsican independence fighters.

Over the past 30 years, more than 9,000 bombings have been carried out, as well as a number of political assassinations. Among those was the 1998 killing of the French prefect to Corsica, Jean-Claude Erignac. Eight people are on trial in Paris in connection with that assassination, although the main suspect, Yvan Colonna, is still at large.

French President Jacques Chirac has long been skeptical about giving Corsica greater autonomy, but he now backs the referendum. Still, the outcome is far from clear, since a number of Corsican lawmakers from Mr. Chirac's own party are urging voters to reject the measure.

If the referendum fails, it would amount to a stunning defeat for Mr. Raffarin's government and the prime minister's goals of decentralizing other aspects of French decision-making.

"Etienne Schweisguth is an analyst at the Paris-based Center for the Study of French Political Life," said Etienne Schweisguth. "He says Mr. Raffarin will be hard pressed to find alternatives, if the Corsica referendum fails. A previous effort to grant the island limited autonomy was judged unconstitutional."

The Corsican vote is being closely watched by other local autonomy movements in France, such as the Bretons and the Basques. It offers one, limited step toward the kind of powers now enjoyed by local governments in Spain's Basque region, for example, or in Scotland.

Daniel Keohane, an analyst at the Center for European Reform, in London, says that, as the European Union grows, so too will regional decision-making.

"The Corsican example does fit into a general pattern across Europe," he said. "It's kind of ironic, in a sense. On the one hand, you have more and more cooperation between different nation-state governments, and different national governments, giving up certain powers to Brussels to run the common space. And on the other hand, you have the process going downwards, giving more power to regions."

But Mr. Schweisguth of the French center believes that, regardless of the outcome of Sunday's referendum in Corsica, France is unlikely to change its centralized political system anytime soon.