Ron Brownstein: “For most of the 20th century, it was common for members of Congress to break from their party’s dominant position on key votes — even when that placed them in opposition to a president from their own side. That tendency was visible for years among Republicans from the East and West Coasts, and even more pronounced among the Southern and rural Democrats who became known as ‘blue dogs.’”
“But tolerance for defection on big congressional votes has waned over the past generation. The engine of the change has been the ideological re-sorting of the electorate, which has left each party with a voter base that holds more uniform views on major issues.”
“In both parties and in both chambers, that has encouraged a transition toward a quasi-parliamentary system, with legislators from each party voting more in lockstep with their own side, and in opposition to the other.”

