Royal, a Socialist, wants the world's leading powers to be stricter with Iran over its nuclear program. Right-winger Sarkozy wants to forge stronger ties with Washington. Both say they will get tough with countries violating human rights.

Despite the rhetoric, analysts say the winner of France's presidential run-off ballot on Sunday will probably not stray far from where outgoing President Jacques Chirac left off.

"I think room for maneuver is limited," said Thierry de Montbrial, head of the French Institute of International Relations (IFRI) think-tank.

Royal and Sarkozy have said they intend to continue much of Chirac's popular foreign policy, particularly in the Middle East, and will seek to give it their own twist.

Royal has repeatedly said Iran should be prevented from having access to civilian nuclear technology because of fears it is secretly developing nuclear weapons, a charge Tehran denies.

Her position goes well beyond the common stance negotiated between France, the United States, Germany, Britain, China and Russia. They are trying to persuade Iran to give up its most sensitive technology, which could be used to generate electricity or make bombs, in exchange for incentives.

"On an issue as subtle, as difficult as Iran ... how could one imagine that the newly elected president would be able to say 'Forget it, we're starting all over again from scratch'? It makes no sense," Montbrial said.

Royal's campaign began with a series of diplomatic gaffes.

She earned a public rebuke from Canada after expressing sympathy with the idea of independence for its French speaking Quebec province, and in Beirut she said she agreed with a Hezbollah lawmaker on the "insanity" of U.S. foreign policy, shortly before heading to U.S. ally Israel.

Royal amended her Beirut comment shortly afterwards but her opponents still use it against her. "We do not need someone who changes her mind as often as she changes her skirt," Defense Minister Michele Alliot-Marie told a Sarkozy rally on Sunday to thunderous applause.

Sarkozy has come under attack for his overtures to Washington, in particular a trip to the United States where he briefly met President George W. Bush and criticized the way in which France opposed the U.S.-led invasion of Iraq in 2003.

"I did not and I will never go and apologize to President Bush for France's position on refusing to send our troops to Iraq," Royal told France 2 television last week. That prompted Sarkozy's camp to insist he did not apologize.

Analysts said talk of 'Sarkozy The American', an insult in a country where anti-Americanism runs deep, is an exaggeration.

"I suspect Americans who think they'll have a pro-American policy from Sarkozy will be disappointed," said Joseph Nye, a professor of international relations at Harvard University.

French-U.S. relations improved in 2005 when both sides agreed to end their feud sparked by Chirac's refusal to back the Iraq war. They are likely to improve further whoever wins on Sunday, Nye said.

Sarkozy and Royal are more than 20 years younger than Chirac and both say they want to do more than he did on human rights. They want more pressure on Russia over abuses in Chechnya, on Sudan over Darfur and on China.

But the realities of power could short-circuit these ideas. "What they have in common is that they will back down," IFRI senior research fellow Philippe Moreau Defarges said.

"If France takes a hard line on Russia, Russia will very quickly turn to the other European partners, notably Germany and the United Kingdom."

Sarkozy, like German Chancellor Angela Merkel, wants a quick agreement on a slimmed-down treaty replacing the stalled EU constitution rejected by French voters in 2005. Royal wants to add social elements to the constitution text and put it to a referendum, a lengthy and potentially hazardous venture.

Sarkozy is also strongly opposed to Turkey joining the European Union.

Whoever wins on Sunday, Chirac will enjoy one advantage over his successors -- mastery of English gained from a student stay in the United States.