Blanc stood for election in the 2002 legislative elections in the third electoral district of Paris, running under the banner of the Énergies democrats (Democratic Energies) and winning 9.63% of the vote. He was elected to the National Assembly to represent the third district of Yvelines on 15 December 2002, replacing Anne-Marie Idrac, who had stood down to become president of the RATP. Winning in the first round, Blanc became a member of the UDF party group in the National Assembly.