Poniatowski took a founding part in the Independent Republicans (RI) party, and became an RI deputy for the Val-d'Oise in 1967, as well as the general secretary of the Confederation of the Independents before taking the presidency of the party's successor, the Republican Party, in 1975. He was elected mayor of L'Isle-Adam (France) in 1971. Bernard Lehideux served Poniatowski as of his office in 1969. Poniatowski was then named Minister of Public Health and Social Security from 5 April 1973 to 27 May 1974, under the government of Pierre Messmer. Minister of the Interior and State Minister (1974–1977) Poniatowski succeeded Jacques Chirac on 24 May 1974, and served the post until 1977. Considered as the main organisator of Valéry Giscard d'Estaing's victory at the 1974 presidential election, he was named Minister of State and Minister of the Interior on 27 May, which changed the official protocol of the Republic: the most important minister was not anymore the Minister of Justice. Although he was a strong-handed Interior Minister, he suppressed the personal registers (fiches signalétiques) which customers of a hotel were to sign (a custom in force in many countries). In August 1975, he sent the military to repress the nationalist rebellion headed by Corsican Edmond Simeoni who had illegally occupied a wine cave in Aleria. Two gendarmes were killed during the assault, leading him, along with Jacques Chirac, of being accused of a large part of the responsibility in the violence which then hit Corsica. Following the assassination of Prince Jean de Broglie, a Giscardian deputy, L'Express (January 1977) and then Le Canard enchaîné, in 1980, published documents alleging that Poniatowski had known in advance of the death threats on de Broglie, and had not acted accordingly. The satirical newspaper recalled that de Broglie had been treasurer of the Independent Republicans, and tied to the Matesa scandal, which allegedly funded the RI. Soon after this affair, and the failure of the right-wing at the March 1977 municipal elections, Poniatowski quit the Ministry of Interior and would not be called again as minister. 1980s Poniatowski was a founding member, in 1978, of the Union for a French Democracy (UDF), the liberal and Christian-Democrat party which backed Valéry Giscard d'Estaing and tried to rival Jacques Chirac's neo-Gaullist Rally for the Republic (RPR). Until 1981, Michel Poniatowski was ambassador and personal representative of President Giscard. He was an MEP from 1979 to 1989,