'The Carla Effect': the French president's new style coach (AFP)

PARIS (AFP) - In three months, Carla Bruni has metamorphosed from catwalk femme fatale into Frances first lady, giving up her high-heels, rustling up a new wardrobe oozing understated chic -- and shelving her steamy talk of polygamy.

As President Nicolas Sarkozy wraps up a roller-coaster first year in power humbled by a collapse in popularity, the 40-year-old supermodel-turned-singer has proved a hit with the French public in her new role at his side.

People-watchers even see Bruni as the driving force behind Sarkozys recent style makeover, coaching him to shed the "Bling-Bling" tag earned for his flashy tastes and tone down his impetuous character to seem more statesmanlike.

"It is too soon to measure the wifes influence on her husband. But there is no doubt it is strong," said political analyst Philippe Braud, of Sciences Po institute in Paris. "She brings him stability."

The couples jet-setting romance and marriage in February, coming three months after Sarkozys divorce from his second wife Cecilia and set against a French mood of deepening economic gloom, was blamed for sending his ratings into a tailspin to a record low of 32 percent.

But as the first lady skilfully choreographed her first state visits -- from curtseying for Queen Elizabeth II to cradling orphans in Tunisia -- French commentators have started to talk admiringly of a "Carla Effect".

"She has scored points in the last few months," said Braud. "The trip to London was the turning point. She didnt put a foot wrong."

Armed with the know-how of her catwalk days, Bruni went for a demure, retro dress style -- complete with flat pumps to avoid showing up the shorter Sarkozy -- that drew admiring comparisons with Jackie Kennedy in the British press.

In recent months, observers suggest she has gently nudged the 53-year-old Sarkozy towards better-tailored suits, elegant shirts -- and away from his much-mocked luxury wristwatches and aviator sunglasses.

After weeks of hyper-exposure in the media, they are now keeping their private life private: their weekend getaways -- to Marrakesh or Brunis sumptuous Riviera villa at Cap Negre -- are kept hidden from the paparazzi.

Bruni even coaxed her pop-culture loving husband to watch a high-brow play at the Comedie Francaise in Paris -- where the pair were spotted slipping in as the lights went down, and leaving before the curtain call.

"Nicolas Sarkozys advisors are relying on Carla to make the turbulent president more calm and respectable" wrote the celebrity magazine Gala.

"I think she is teaching him some manners," quipped Braud.

Bruni is still a fleeting presence at the presidential palace: she and Sarkozy spend weekday evenings at her Paris mansion where she is recording her new album, due out this summer, after which she plans to take up her Elysee offices and focus on humanitarian work.

Polls suggest the first lady, who openly backed Sarkozys left-wing rival in the election last May, has conquered the French public on both sides of the political divide with nine in 10 describing her as "elegant" and "modern."

The French president himself seems in awe of his wifes beauty, her culture and knowledge of five languages, and regularly sings her praises in public.

And the French press -- with the exception of a gently mocking spoof "Diary of Carla B." in the satirical Canard Enchaine -- has so far been kind to her.

But despite her apparent coaching, there is so far no sign of Brunis popularity rubbing off on the president.

Experts say the rapid sequence of divorce and remarriage, together with an undignified incident in which Sarkozy insulted a bystander at a farm show, made him appear erratic and vulnerable, just as the French needed reassurance about the faltering economy.

"Even people who were ardently pro-Sarkozy are furious, terribly disappointed, they feel he wasted his victory," said political analyst Jean-Luc Parodi, predicting the global economic crisis and unpopular reforms would keep Sarkozy in negative ratings for the foreseeable future.

"Bruni has very cleverly chosen a strategy of discretion and modesty. But we cannot expect all that was spectacularly destroyed in the past few months to be rebuilt from one day to the next."