I am not sure you even understand how we amend a Constitutional amendment here in the US. If you did, you would know what I mean. It was designed on purpose to not be amended by popular opinion or vote. A amendment must be approved by 3/4 of the states and then 2/3 of Congress to ratify. You can have 70% of the public as a whole in favor of such and still fail based on a lack of enough of the smaller populated states to be in favor of it.
An amendment may be proposed and sent to the states for ratification by either:
The United States Congress, whenever a two-thirds majority in both the Senate and the House of Representatives deem it necessary;
OR
A national convention, called by Congress for this purpose, on the application of the legislatures of two-thirds (currently 34) of the states.
To become part of the Constitution, an amendment must be ratified by either (as determined by Congress):
The legislatures of three-fourths (currently 38) of the states, within the stipulated time period—if any;
OR
State ratifying conventions in three-fourths (currently 38) of the states, within the stipulated time period—if any.
Upon being properly ratified, an amendment becomes an operative addition to the Constitution.