Violates the constitution? I’m not a constitutional scholar, but that sounds like a ridiculous argument. Article 1, section 3: “The Senate of the United States shall be composed of two Senators from each State…”

The 14th amendment introduces “equal protection,” speaks specifically about representation, and says nothing about changing the makeup of the senate.

(Edit: And even if it did, the 17th amendment restates that each state gets two senators, and would supersede the 14th.)