Colombia, national Plebiscite [ATP] - Someter a referendo un proyecto de reforma constitucional

Article 374.
The Political Constitution of Colombia may be amended by Congress, a Constituent Assembly, or by the people through a referendum.

Article 378.
Upon the initiative of the government or the citizens under the terms of Article 155, the Congress, through a law which requires the approval of the majority of the members of both chambers, may call a referendum on a bill of constitutional reform which Congress would also include in the law. The referendum will be presented in such a manner that the voters may select from the agenda of the various items those on which they wish to vote favourably and those they which they wish to defeat. The approval of constitutional reforms by means of a referendum requires the affirmative vote of over half the voters and the number of these must exceed one-fourth of the total number of citizens included in the electoral rolls.

Reference: Constititution of Colombia, 1991, (accessed 29.09.2021)

To call a referendum for a constitutional amendment