Blanc also took part in the Pébereau Commission, which calculated France's national debt at €2 trillion. Blanc was a supporter of the presidential candidacy of Nicolas Sarkozy in the 2007 presidential election and became member of the New Center party during the legislative elections, in which he was re-elected in the first round. Between 2002 and 2007, Blanc served as president of Énergies democrats and the founder of Énergies 2007, movements which supported reforming the French state and pursuing further European integration. As Vice-President of the New Center, he ran in the 2008 French local elections to become the mayor of Le Chesnay, a wealthy western suburb of Paris, but secured only 36.28% of the vote and failed to unseat the incumbent mayor in a three-way race. On March 18, 2008, Blanc was appointed Secretary of State of the Région Capitale ("Greater Paris"), a new position in the French Government of François Fillon. Blanc was responsible for crafting the legal framework for the “Greater Paris” project, which entered into law in May 2010 and provided for a network of automated metro lines surrounding Paris. After the French Parliament's enactment of the Greater Paris law, Blanc announced his resignation from the government on July 4, 2010. In June 2010, after Blanc dismissed his chief of staff, allegations regarding his tax situation appeared over the next eight days in France's Canard Enchaîné newspaper. One week later, the same newspaper claimed that Blanc allegedly used his secretarial budget to purchase cigars worth €12,000 over the course of ten months, a claim which was widely reprinted by French media. In an interview with the Figaro, Blanc accused his former chief of staff Guillaume Jublot, who had been recently fired by Blanc, of feeding false information to the Canard Enchaîné. After discussions with then-Prime MInister François Fillon, the two men released a statement in which they jointly declared it "suitable that Mr. Blanc honors his personal expenses in full." The matter helped accelerate Blanc's decision to leave government, with the opposition and elements of press speculating that his exit might be a tactic by the ruling UMP to turn media attention away from President Nicolas Sarkozy's role in the Woerth-Bettencourt scandal. The UMP denied any such links. Blanc retook his seat in the National Assembly after leaving the government in August 2010 and declined to stand in the 2012 legislative elections.