I think it was a post of yours several months ago that made me realize that the problem with the 17th was that it converted the Senate from a body of the states to a body of the parties. That problem then metastasized into the courts via advice and consent.
It would be much harder for strict party alignment to operate in a Senate where the members are selected by independent state legislatures, than it is today via party funding of constant general elections.
-PJ
Like any employee, politicians will play the tune of their employers. Senators and Presidents are products of their parties.
Remove them from the party process of climbing, promising, taking campaign funds, and general demagoguing. Make them responsible to a couple hundred state legislators in fifty states and watch our republic recover.