Having originally received a traditional, Roman Catholic education, Nin was a member of the National Party and Intendant of Cerro Largo from 1985 until 1994.

Among the issues with which Nin Novoa has been identified has been the successful efforts to prevent the privatization of water supplies and other services, amidst fears of its effects on users living in the interior of the country.

By the end of 2007 the Nin brothers were facing hostility from ostensible colleagues, including Juan Domínguez, and others, in the ruling Frente Amplio coalition.

Nin Novoa's presence in the government of Tabaré Vázquez exemplified the highly diverse nature of the coalition of forces which it represented.

The Progressive Alliance forms part of the Liber Seregni Front along with Uruguay Assembly of Danilo Astori and New Space of Rafael Michelini, reflecting moderate, centre-left to centrist tendencies.