He was its only member in the National Assembly, having been elected for Essonne's 8th constituency beginning in 1997; he was previously mayor of Yerres from 1995 to 2017.

[9] Dupont-Aignan began his professional career in politics as a civil administrator and working in several ministerial offices, including that of the Minister of National Education and the Environment.

Dupont-Aignan joined Rally for France in 1993[10] and then began serving in Michel Barnier's ministry of the environment in February 1995 though he refused to support either Édouard Balladur or Jacques Chirac in their presidential campaigns that year.

[11] In the early 1990s, the city of Yerres was in 20 million euros in debt following the closure of a major aquatic centre that shut down a few months after its opening.

[14] Dupont-Aignan took this further by cancelling infrastructure initiatives set by the previous mayor and developed a cheaper plan[15] that included creating communal housing.

Dupont-Aignan also campaigned for a "No" vote in the 2005 French European Constitution referendum, abandoning perceived Gaullist principles.

Following his failure to gather the 500 signatures necessary to run, Dupont-Aignan was reelected in his constituency of Essonne 8th though he was no longer a part of the presidential majority due to disagreements with President Sarkozy over taxes and a pro-American foreign policy,[21][22] voting alongside the Socialist Party on several occasions.

[30] On 7 March 2017, Dupont-Aignan secured the necessary 500 signatures to run in the 2017 presidential election[31] before releasing his manifesto the following day in the form of a book.

[32] Shortly after the beginning of the first round, Dupont-Aignan denounced Emmanuel Macron, saying that he "served the interests of the rich"[33][34] and accused Serge Dassault, the owner of Le Figaro, of harassing him through text messages in an attempt to get him to renounce his candidacy in endorsement of François Fillon.

[43] Marine Le Pen pledged in return to appoint him as Prime Minister of France should she win.

[44][45][46] The electoral alliance between Debout la France and Front National gathered protesters in Dupont-Aignan's commune, Yerres.

[citation needed] Dupont-Aignan was reelected during the legislative election of 2017; he resigned as Mayor of Yerres later that year and was succeeded by Clodong.

[44][45] Although he shares many policies and views with Marine Le Pen,[45] he is considered less hardline than she and has criticised her in the past.