Nicolas Sarkozy, a leading contender for the French presidency in elections next spring, said Friday that he would seek a radical restructuring of European Union institutions and the suspension of membership talks with Turkey if he won.

His most controversial proposal, and one that appeared to be directed at French voters more than other EU nations, was that the Union define its borders to restrict expansion - effectively blocking Turkish membership.

Turkey has presented unique problems in the enlargement debate because of its majority Muslim population.

"We now have to say who is European and who is not," said Sarkozy, interior minister in the current government. "Leaving this question unanswered is no longer possible."

Sarkozy's speech directly challenged Ségolène Royal, currently the leading contender among Socialists seeking their party's nomination. The Socialists shied away from the issue of European integration after the French referendum on the European constitution provoked a deep rift last year. Royal, who like Sarkozy campaigned for approval of the constitution, has remained silent on Turkish membership since the charter was rejected.

But Sarkozy, who has already made immigration a key election issue, has now forced Europe to the forefront of the campaign.

"I have no intention of leaving Europe out of this debate or hiding my position," Sarkozy said.