The virtually lockstep Republican defense of President Donald Trump so far during his impeachment trial marks a new milestone in the Senate’s long-term evolution into a more partisan and regimented institution that demands unwavering party loyalty and punishes the freewheeling independence that characterized the great legislators through the body’s history.
That transformation is grounded in a fundamental reordering of the political landscape: Over the past generation it has grown much more difficult for either party to win Senate seats in states that usually prefer the other party in presidential elections. CONT.
Ronald Brownstein, CNN