The Spanish diva hoping to upstage Mme Sarkozy

She sings. She is a middle-aged beauty. She belongs to the First Wives' Club. And her name is not Carla Bruni.

It's Sonsoles Espinosa, the opera-singing wife of Spanish Prime Minister Jose Luis Rodriguez Zapatero. When the French President, Nicolas Sarkozy, lands in Spain for a two-day visit today, the paparazzi will be out in force to scrutinise every outfit and gesture of the glamorous French first lady.

But the former supermodel and pop singer Carla Bruni-Sarkozy could well be upstaged by the blonde Señora Espinosa. The perceived rivalry between the two tall photogenic wives has heightened the titillation caused by the French President's recent gaffe, in which he questioned Mr Rodriguez Zapatero's intelligence. The duelling divas have nearly eclipsed all talk in Spain about serious matters facing the two heads of state, including Basque separatism.

The svelte wife of Mr Rodriguez Zapatero is unlike her French peer in many respects. Her love life, for a start, is beyond dull. The Spanish tabloids have failed to turn up any steamy liaisons before Ms Espinosa met Mr Rodriguez Zapatero at law school in northern Spain in 1981. Their courtship, dragged out in true Spanish style, lasted nine years.

Ms Espinosa is not especially interested in fashion, although when caught on camera she never fails to make a splash in body-hugging, sleeveless numbers that showcase her athletic torso. She has been known to crown her cropped locks with a hair extension for formal affairs and to delegate wardrobe decisions to the Spanish designer Elena Benarroch.

When Ms Espinosa takes the French first lady to lunch during a tour of the Spanish capital, nobody expects them to talk about Dior's latest – although they might also chat about music. But here, too, a gulf divides. Sonsoles Espinosa, a soprano, has never had a hit like her rival. She is more familiar with Spain's Royal Theatre than a recording studio. She recently performed in Paris, however, in Richard Wagner's The Fairies.

While Mme Bruni-Sarzkozy is a PR dream for her husband, Ms Espinosa shuns publicity. "They elected him, not me," she once told reporters. She is usually absent from acts of state and keeps her politics under wraps.

The first wife has no determined role in Spanish politics, partly because the cheek-kissing photo opportunities are often relegated to the royal family. But Ms Espinosa caused a stir when she skipped the G20 in London. Some fear that her absence at international summits could hurt Spain's image abroad. But in a poll conducted on the matter by Telecinco, more than 80 per cent of viewers supported her back-seat role.