Article 1 gave state legislatures the power to elect these officials; the 17th amendment overrode that
The Congress shall have Power To lay and collect Taxes, Duties, 
Imposts and... [DOC] [TLE] 17th Amendment to the U.S. Constitution: Direct Election of U.S. ... [PAR] The first proposal to amend the Constitution to elect senators by popular vote ... 
Several state legislatures deadlocked over the election of senators, which ...