He soon rose to prominence in the National Assembly, becoming the friend of most of the leaders of the party originating in the Third Estate, and formed with Adrien Duport and Alexandre Lameth the group known during the Constituent Assembly as "the triumvirate". Together these three would later be principal figures in the formation of the Feuillants, the breakaway party from the Jacobin Club dedicated to a moderate course supporting constitutional monarchy. Barnave took part in the conference on the claims of the three orders, drew up the first address to king Louis XVI, and supported the proposal of Emmanuel Joseph Sieyès that the Assembly should declare itself "National". Until 1791, he was one of the preeminent members of the club known later as the Jacobin Club, of which he drew up the manifesto and first rulebook.
He soon rose to prominence in the National Assembly becoming the friend of most of the leaders of the party originating in the Third Estate and formed with Adrien Duport and Alexandre Lameth the group known during the Constituent Assembly as "the triumvirate" Together these three would later be principal figures in the formation of the Feuillants the breakaway party from the Jacobin Club dedicated to a moderate course supporting constitutional monarchy Barnave took part in the conference on the claims of the three orders drew up the first address to king Louis XVI and supported the proposal of Emmanuel Joseph Sieyès that the Assembly should declare itself "National" Until 1791 he was one of the preeminent members of the club known later as the Jacobin Club of which he drew up the manifesto and first rulebook