Which institutions can propose an alternative to proposals contained in a citizens' initiative?

No provision in this regard, but the President has the power to amend the text of the initiative in the case of legislative proposals

CONSTITUTION OF THE REPUBLIC OFECUADOR (2008)

http://pdba.georgetown.edu/Constitutions/Ecuador/english08.html

Article 103. Grass-roots legal andregulatory initiatives shall be exercised to propose the creation, amendment orrepeal of legal regulations to the Legislative Branch of Government or anyother body that has a regulatory jurisdiction. It must benefit from the backingof a number accounting for no less than zero point twenty-five percent (0.25%)of the persons registered in the voter registration list of the correspondingjurisdiction.

Those who propose a grass-roots initiativeshall participate, by means of their representatives, in discussing the projectin the corresponding body, which shall have a term of one-hundred eighty (180)days to review the proposal; if the proposal is not reviewed within thosetime-limits, it will enter into force.

When it involves a bill, the President ofthe Republic shall be able amend the bill but not to veto it completely.

For the submittal of constitutional amendment proposals, thebacking of a number accounting for no less than one percent (1%) of the personsregistered in the voter registration list shall be required. If the LegislativeBranch does not review the proposal within a term of one year, the proposerswill be able to request the National Electoral Council to call for areferendum, without the need to provide the eight percent (8%) backing of thoseregistered in the voter registration list. While one grass-roots proposal to amendthe Constitution is being processed, no other can be submitted at the sametime.

Ley Orgánica Electoral y de OrganizacionesPolíticas de la República del Ecuador, Código de la Democracia (Democracycode), del 27 de abril de 2009

http://idbdocs.iadb.org/wsdocs/getdocument.aspx?docnum=35394757

Art. 194.- Apartir de la notificaci?n a la Asamblea Nacional o

a la instanciarespectiva empezar? a correr el plazo de ciento ochenta

d?as para tratar la propuestade iniciativa popular normativa; si no

lo hiciere, entrar? envigencia la propuesta.

Cuando se trate de un proyectode ley, la Presidenta o

Presidente de la Repúblicapodr? enmendar el proyecto pero no vetarlo

totalmente.