A lawyer by training,[1] she was the first woman to become president of the National Assembly of Nicaragua,[2] where she served as a deputy for 22 years.

However, César prevailed the following year, replacing Argüello in 1991.

[4] In 1996, Argüello ran for President of Nicaragua as a member of the Popular Conservative Alliance (APC).

[5] Though in the previous term, both the Presidency and Vice-Presidency had been held by women—Chamorro and Julia Mena Rivera, respectively—few other women served in the Chamorro administration and in 1996 Argüello was the lone woman among 23 presidential candidates.

[5] In 2007, Argüello allied with the Sandinista National Liberation Front (FSLN), but broke again with the ruling party in 2012 over the re-election of FSLN leader Daniel Ortega as President, saying the Supreme Court's ruling allowing Ortega a third term violated the Nicaraguan Constitution as well as legal precedent barring anyone from serving three terms as President or serving for two consecutive terms.