Why is the Senate gridlocked?

The Senate is gridlocked. Political scientists do not fully understand why. More than twenty years ago, Keith Krehbiel observed that “no existing theory or school of thought provides a precise explanation for the basic facts concerning gridlock.” Despite the many contributions Krehbiel (and others) have made to our understanding of Congress since then, it remains the case today that no existing theory or school of thought can explain gridlock, especially in the Senate.

The existing theories, including Krehbiel’s Pivotal Politics model, along with much of the recent work that has examined the Senate empirically, offer two general explanations for “the pervasive problem of legislative gridlock.” Some see the phenomenon as a consequence of the ideological polarization of legislators’ (or voters’) preferences. Others believe that gridlock is caused by a zero-sum contest between Democrats and Republicans battling for majority control of the Senate.

Nevertheless, both explanations emphasize exogenous forces, like ideology and partisanship, as causing gridlock, instead of senators’ actions inside the institution. Consequently, both accounts are premised on the same assumption- that senators act in ways that cause gridlock. Preference-based explanations assert that ideologically polarized senators will act to advance their agenda while trying to block their opponent’s priorities. Likewise, party-based explanations contend that Democrats and Republicans, competing for majority control of the Senate, will act in ways that accentuate the differences between the two parties to win more seats in the chamber.

Take, for example, the depiction of Congress as “a forum for partisan competition” by Gregory Koger and Matthew J. Lebo in an excellent new book, Strategic Party Government: Why Winning Trumps Ideology. A recent peer-reviewed article on the Senate similarly describes the amendment process as “plagued with increased polarization and partisan maneuvering.” Frances Lee similarly observes that “far from streamlining Senate procedure, party polarization has tied the chamber in knots, reducing the legislative productivity of Congress as a whole.”

Works like these generally contend that partisan competition is especially damaging in the Senate because it is easier for senators to differentiate themselves from one another by exploiting their ability to offer floor amendments. As such, minority-party members should have an easier time accentuating their differences with the majority party by forcing partisan message votes in the amendment process.

But the present-day actions of senators, both Democrats, and Republicans, inside the chamber, challenge the conventional wisdom. Consider the Senate’s recent amendment activity. The number of amendments filed by senators during legislative debate, as well as the number that they eventually offer, has declined precipitously. (See Figure 1 above.)

As of July 22, senators have offered 90% fewer amendments in the 116^th Congress than they did in the 115^th. Senators offered, on average, 1773 amendments in every Congress from the 97^th to 114^th. The 599 amendments that senators offered during the 115^th Congress, the most recently completed two-year period, represents a 66 percent decrease in amendment activity from the average.

The Senate’s amendment activity remained relatively consistent, fluctuating up and down every two years, until the 111^th Congress, when it began the current downward trajectory. The number of amendments senators offered fell by 30 percent in the 111^th Congress, 23 percent in the 112th, and 44 percent in the 113th.

Frustrated by the lack of amendment opportunities, Republicans committed to increasing opportunities for rank-and-file senators to offer amendments in the 114^th Congress. The number of amendments senators offered rebounded after Republicans regained control of the Senate in the 2014 elections, increasing 94 percent in the 114^th Congress.

These gains were temporary. The Senate’s amendment activity soon resumed the downward trajectory characteristic of prior years, falling by 43 percent in the 115^th Congress. At the present rate, the 116^th Congress is on track to set an all-time low.

The near-total collapse in amendment activity on the Senate floor is unprecedented, at least in the modern era. According to a Washington Post-ProPublica study, “Junior senators have fewer opportunities to wade into the issues of the day, largely because Senate leaders limit the number of votes on amendments to proposed legislation. The number of such votes has shrunk to an all-time low under McConnell, less than 20 percent of all roll calls, from 67 percent 12 years ago.”

The reduction in amendment opportunities impacts senators in both parties.

It has also yielded considerably fewer recorded votes on amendments.

Those that senators do consider are typically disposed of by voice vote and unanimous consent (not by recorded vote).

Disposing of amendments by voice vote and unanimous consent makes it difficult, if not impossible, for the parties to use them for messaging purposes or to otherwise differentiate their members from one another. Finally, vote outcomes on both legislation and amendments are usually bipartisan.

All of this suggests that our present inability to explain why the Senate gridlocks is due, in part, to our overlooking what happens when senators try to legislate. That produces a gap between how we understand the Senate and its reality. Bridging that gap requires that we consider more fully what happens when senators come together in a specific place to participate in a particular kind of practice.