He was elected in 1789 by the clergy of the bailliage of Nancy to the Estates-General, where he soon made his name as one of the group of clerical and lay deputies of Jansenist or Gallican sympathies who supported the Revolution. He was one of the first of the clergy to join the third estate, and thus contributed notably to the union of the three orders; he presided in the session that lasted sixty-two hours while the Bastille was being attacked by the mob, and spoke vehemently against the enemies of the nation. He later took a leading role in the abolition of the privileges of the nobility and the Church.