AFTER a series of scandals under the outgoing centre-right president, Nicolas Sarkozy, François Hollande campaigned as the Socialist candidate last year with the promise of creating an “exemplary republic”. After he won, his ministers were made to sign a charter of ethics. He cut their pay by 30%, and told them to swap their ministerial cars for the train.This model of modest virtue has, however, been shattered by the confession of Jérôme Cahuzac, the former Socialist budget minister who was also in charge of a crackdown on tax evasion, that he had lied about a secret foreign bank account to the president, parliament and the country. His admission has rocked Mr Hollande’s presidency, and is threatening to undermine not only his government’s moral authority but also its ability to get things done.The allegations of a secret Swiss account were dug up last December by Mediapart, a left-wing investigative-news website. Mr Cahuzac had held the account for 20 years, the website claimed, before transferring its balance to a new account in Singapore in 2010. Speaking before parliament that month, an indignant Mr Cahuzac denied anything of the sort. “I do not have, and have…