The Constitution insisted that each of the states be represented by two senators chose by their state legislatures. In 1913 the 17th amendment was ratified which destroyed the legislative integrity of Congress.
At that point the states lost their representation and the senate became a second version of the House of Representatives. This change created a tyranny of majority where the will of the majority could legally deprive the states of their equal represenation in the senate.
No State, without its Consent, shall be deprived of its equal Suffrage in the Senate.