Barbara Boxer and the Rise of Democratic Partisan Discipline

by Derek Willis,

It might seem unremarkable that Senator Barbara Boxer of California, who announced on Thursday that she would not seek re-election, voted with a majority of her Democratic colleagues 98 percent of the time during the past two years.

But consider this: Her voting score was a career high and still placed her only 27th among Democratic senators in the 113th Congress. That result demonstrates the unusually high level of partisan discipline maintained by Harry Reid, who was majority leader. Even with several red-state Democratic senators straying from the party on certain votes, each Democratic senator voted with a majority of his or her colleagues 97.4 percent of the time on average, the highest level in recent history. (The Senate maintains electronic vote data only back to 1989).

Before 2013, only one Democratic senator in the past 20 years voted with most of her colleagues at least 98 percent of the time: Barbara Mikulski of Maryland, who did so during 2009-2010. Twenty-nine Senate Democrats met that threshold for the most recent Congress.

Republican senators have rarely approached the level of unity shown by Democratic ones in recent years, even when in the majority. Their highest average score of 93.5 percent was in 2003-2004, when George W. Bush was president and the G.O.P. controlled both houses of Congress. In the most recent Congress, Senate Republicans had an average score of 87.2 percent. With a new majority in place, it’s likely that figure will go up at least slightly in the next two years.

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