Both parties fundamentally saw themselves as in a cooperative enterprise ("We are all working to lead the country forward, and though we have different views on how to do that, we will acknowledge that we agree on that much and will find ways to work together per the Constitution to make it happen" ). After 9/11 that comity broke down. Judge Merrick Garland* was ultimately the greatest victim of that breakdown, and it cost him a seat on the Supreme Court.

This cyclic degeneration of the comity of Washington got out of control over the last two decades. How did it happen? As I recall the events:

Round 1 (2001) – Miguel Estrada,* a conservative lawyer, was nominated to the DC Circuit Court of Appeals by Bush II. He was eminently qualified (per an honest Lefty law professor friend of mine), but Democrats blocked him on the grounds of his being appointed by Bush.

Round 2: The turnabout was Republicans blocking most Obama judicial nominees via filibuster. 

Round 3: Harry Reid lost his temper at McConnell and at his behest the Dems changed the rules so that judicial nominees below the Supreme Court level couldn't be filibustered (the "Reid Rules"). The first beneficiaries were three eminently qualified judges for the DC Circuit.