PARIS, FRANCE - France went to polls on Sunday for the final round of local elections that look set to inflict heavy losses to President Nicolas Sarkozy's right-wing party as the left vies for control of the top four cities.

The elections are the first major test of Sarkozy's popularity since he took office 10 months ago on a platform that called for sweeping economic and social reforms.

Tumbling in the opinion polls, Sarkozy has signalled that the election results will lead to some adjustments, but that there will be no retreat from his drive to tackle France's ills.

But the second city of Marseille was shaping up as the big prize, with the incumbent right-wing mayor locked in a tight race against a Socialist who has allied with a centrist candidate.

Another citadel of the right, Toulouse in the southwest could fall to the left after 37 years of right-wing administration in France's fourth largest city and home to aeronautics giant Airbus.

Strasbourg in the east is also set to swing left after Socialists called on voters to "punish" Sarkozy and his government at the ballot box on Sunday.

Sarkozy was preparing what the Elysee presidential palace has termed "minor adjustments", revamping his communications team and appointing new faces to junior posts in government.

"The people will have spoken. I will naturally take into account what they expressed," said Sarkozy last week during a trip to the Mediterranean city of Toulon.

In the lead up to the vote, Sarkozy has kept a low profile as he battled to halt a freefall in opinion polls since January that has seen him lose some 30 points. Fewer than four in 10 voters now approve of his performance.

Pollsters attribute the drop to pessimism about the economy coupled with perceptions that the president is distracted by his personal life, after his divorce from second wife Cecilia and marriage to model-turned-singer Carla Bruni.

Political commentators say an image makeover is in order to rekindle voter approval of the 53-year-old president, criticised for a brash and at times extravagant style that earned him the nickname "the Bling-Bling president".

Le Monde newspaper last week quoted Elysee sources as saying that Sarkozy would now cultivate a more "presidential image", by for example banning photos of his daily jogs in a t-shirt and dark aviator sunglasses.

"A penalty from the municipal elections would not tarnish the legitimacy of the president," wrote political analyst Alain Duhamel last week.

"But it incites, invites and presses the head of state to take action, to rectify his stance, in short, to show that he is a realist," he said.

Leaders of the governing Union for a Popular Movement (UMP) have rejected suggestions that the results were a rebuke of Sarkozy's policies, pointing to the rare first-round election of 14 of the 24 ministers running for local office.

Gains made by the left in the first round were described by Socialists and even right-wing commentators as a "warning" from disappointed voters to Sarkozy.

Socialist Segolene Royal, who lost to Sarkozy in the May presidential polls, has said first-round results amounted to a "vote of censure" and called for a large turnout for Sunday.

But a victory for the Socialists would do little to resolve the problems facing the opposition party as it heads toward a key leadership contest expected later this year.

A big win for Paris Mayor Bertrand Delanoe on Sunday could help him strengthen his hand against Royal in the party leadership race.

Polls opened at 0700 GMT and were to close at 1700 GMT, except in Paris and major cities where they will remain open for an extra hour or two.