Not much, if we are willing to trash our Constitutional Republic. Otherwise, the President must seek concurrence from two thirds of the Senate to nullify the treaty. In my opinion this was a late night "deal" to mollify the public. No more, no less. Good PR for the Republican party, no doubt. My stance is simple. Such a maneuver for political gain is inappropriate. Else the "opposition" (joke) would have stalled it. IMHO it is a bipartisan ploy to garner votes. On both sides of the aisle.
If we are indeed suffering an invasion, and the "War on Drugs" (and illicit smuggled weapons and sex slaves) is a failure; please explain to me why we allow our finest men and women to give the ultimate sacrifice for zero benefit. Simply put, when a muddy creek and some barbed wire can not be controlled; too many "conservatives" demand to throw money at the problem.
With an 80-19 margin for passage, if the Mexican government is unwilling to come to an agreement on this issue, it is quite possible the Senate could vote to nullify the treaty in whole or in part.
I still don't see anything in the treaty prohibiting us from building a border fence. Please explain.
I don't know where you got this idea, but it's not the least bit true. Treaties are not superior to statutes; nor are statutes superior to treaties. The two are Constitutionally equal. If or when they conflict, whichever occurs later becomes the (new) law of the land.