A months-old push by President Nicolas Sarkozy to put a deficit-controlling clause into the constitution has blown into a political storm since he proposed on Tuesday, backed by Germany, that such "golden rules" be enshrined across the euro zone.

The Socialists have refused from the start to give Sarkozy the three-fifths majority he needs to tweak the constitution, but they will be left in an awkward corner if the rest of the 17-nation euro bloc backs the golden rule plan.

Prime Minister Francois Fillon upped the ante by pleading in an interview with Saturday's edition of the daily Le Figaro for all French political parties to show a united front on the idea.

"Francois Fillon is calling for national unity to pay the bill for his bureaucratic waste," snapped Socialist Party leader Harlem Desir in response.

"Since 2007, it's been more about unity of the super-wealthy to share tax favours. At the height of the crisis, the French people are not waiting for the prime minister to publish political editorials, they want a fair and efficient budget."

The French Greens also weighed in against Fillon's plea.

Green presidential candidate Eva Joly called the golden rule idea "economically inefficient and politically absurd" as she kicked off her election campaign in the city of Clermont-Ferrand in mountainous central France.