[3] In 1790, Amar was elected vice-president of the Grenoble directory, and became a deputy to the National Convention for the département of Isère, and joined The Mountain, voting in favor of Louis XVI's execution during his trial.
Sent on mission with Jean-Marie François Merlino [fr] to Ain and Isère in early 1793, he oversaw the levée en masse of 300,000 soldiers brought about by the outbreak of the French Revolutionary Wars and he made widespread arrests of "counter-revolutionaries".
After the ousting of the Girondists from the Convention in late May and early June 1793, Amar joined the Committee of General Security on September 13.
Amar then opposed the establishment of the French Directory in November, and in February 1796 he presented a petition from 'Patriots of '89' urging the re-establishment of price controls on basic foods.
He retired from public life, and lived most of his remaining years in Isère and Savoie, discovering devotional mysticism based on the works of Emanuel Swedenborg.