In 1967 Agüero was chosen to represent the conservative 1966 National Opposition Union (UNO) in the presidential election against the Somoza regime. His campaign was marked by the bloody repression of one of his political rallies in Managua. In 1971 however, Agüero signed the controversial Kupia Kumi pact with Anastasio Somoza Debayle. He was born in Managua, Nicaragua.