Issues in relation to which referendums are optional at the national level
Chile
Answer
Constitutional amendments
Source
PoliticalConstitution of Chile (Constitución Política de la República de Chile) http://aceproject.org/ero-en/regions/americas/CL/chile-constitucion-politica-de-la-republica-de
Articles 4 and 128.
Comment
Referendum might be an option to solve the conflictthat arises when the Executive (President) rejects a constitutional amendmentproject passed by the Congress, and both Chambers of the Congress insist, withthe vote of two thirds of its members, on its approval by the Executive. Inthis case, the Executive shall promulgate the amendment, unless it decides tosubmit the issue to referendum.