Mr Longuet, 48, is the leader of the Republican Party, one of the main components of the centre-right Union for French Democracy (UDF), the coalition partner of Mr Balladur's Gaullist RPR party. The resignation removes one of the strongest supporters of a Balladur candidature for next spring's presidential election.
Over the past month, Mr Balladur has seen his unprecedented popularity levels fall and, this week, Jacques Delors, the most likely Socialist candidate, caught up with him for the first time, according to one opinion poll.
Renaud Van Ruymbeke, an anti-corruption examining magistrate who has turned up a series of cases of illegal party funding on both left and right, asked the Justice Ministry last month to charge Mr Longuet for allegedly paying less than the market price to build a villa in Saint Tropez. The report suggested that the price might be linked to public works contracts accorded in Lorraine where Mr Longuet is the regional council president.Reuse content