The U.S. Senate has become increasingly dysfunctional in recent sessions, prompting posts like this one from Josh Huder and this one from James Wallner. This institution, historically recognized for its bipartisan, compromising nature, is instead witnessing greater levels of obstructionism and brinkmanship. One of the most commonly identified culprits is polarization within the chamber. The figure below plots the ideologies of current Senators and shows a considerable gulf between the two parties, lending support to this argument. Congress is clearly and consistently the least popular branch of government, and gridlock is the most common reason behind this, according to Gallup.


What is driving this polarization? And why has the “world’s greatest deliberative body” refused to do anything to overcome this image? In order to provide answers to these questions, we must first consider the role of parties in government. A party’s primary goal is to move policy in its preferred direction. However, in a highly competitive electoral environment, it is important to construct a minimum winning coalition to maximize the benefits accrued to its members.

As such, the first factor contributing to this perceived polarization is competition for control of the chamber through winning elections. If a bill passes with large, bipartisan support, then the party has not gained much (if any) of an electoral advantage over the opposition. Therefore, from the perspective of the majority party, there is no real incentive to put forward a bill that is popular with a large portion of the minority party. For those in the minority, there is no real incentive to support a measure offered by the majority. As Gore Vidal wrote, “It is not enough merely to win; others must lose.”

In this vein, it is important to also consider the agenda-setting power of the majority leader.  Senate Majority Leader Mitch McConnell was recently quoted as saying “I get to decide what we vote on.” He has also increasingly filled the amendment tree, essentially barring other senators from altering legislation. Therefore, members largely only get straight up or down votes on legislation that the majority is united on and that the minority is opposed to.

Because of this, any issue that does have bipartisan support will generally be dispensed with relatively quickly, probably without a recorded vote. One such example comes from the 115th Congress. Senate Rule XXII governs floor privileges in the chamber. Who is and is not allowed to be on the Senate floor is a somewhat contentious issue and has varied with time. Senators can ask for unanimous consent for someone to obtain the floor on an ad hoc basis, but this practice is generally used only for certain staff. A brief history can be found here.

Despite this history, the Senate passed SR 463 with relative ease. This resolution would allow Senators to bring newborn children onto the floor in order to cast a vote. On April 9, 2018, Senator Duckworth became the first senator to give birth while in office. The resolution was introduced three days later, discharged from committee five days after that, and passed by unanimous consent later the same day. By April 19th, ten days after giving birth, Duckworth brought her infant daughter to the floor to cast her vote on the nomination of Jim Bridenstine to lead NASA.

Leaders from both parties met beforehand with colleagues to discuss concerns, negotiate language, and ultimately worked together to expedite passage. Though this issue is obviously not as salient as the economy or the environment, it shows that senators know how to work together and can enact change in an efficient manner. Why then is this behavior not more commonplace? Because it does little in the way of helping to secure reelection for members.

Another consequence of this search for minimum winning coalitions in a relatively small chamber like the Senate is that each individual vote carries significant weight in determining passage. This is especially true when the majority party only holds a near-bare majority. This is further exacerbated by attempts to reduce the number of votes needed to successfully pass a measure, such as considering legislation under reconciliation rules and reducing the number of votes needed to invoke cloture on nominations (both of which occurred in recent congresses). Strong partisans are likely to vote the party line already, but this puts immense pressure on moderates to decide between supporting their constituents’ preferences or upholding the party brand.

In short, recent rules changes and strategies employed by leaders, coupled with electoral competition for control of the chamber, creates the perception of a deeply polarized political environment, even if an appetite for bipartisanship still exists among some. Indeed, former Senators McCaskill and Nelson, who lost their reelection bids last November, both lamented the increased partisanship witnessed over their careers.

Why then would rank-and-file members subject themselves to an environment where their input on legislation is limited and compromise is not valued? Frankly, they have little to no incentive to do so. Even absent divergent ideological preferences, both parties benefit from the mere perception of distinct differences between them. Preserving the party brand allows voters to easily distinguish between candidates without knowing anything else about them. This reduces information costs for voters, which in turn makes them more likely to turn out to vote.

In addition to reducing the information costs for voting, the perception of polarized parties coupled with increased negative views and animosity towards the opposition means voters also feel supporting one party over the other is more important than ever. This subsequently facilitates messaging and voter mobilization efforts by parties.

To summarize, the parties might not be as ideologically polarized as our measures tend to indicate. However, it is the perception of distance that matters. And as long as parties and members can benefit electorally from polarization, we will witness more steps to further the divide and fewer (if any) to ameliorate the problem.

Filed Under:
Topics: Parties, Campaigns, & Elections
Ryan Williamson
My name is Ryan Williamson, and I am an Assistant Professor of Political Science in the College of Liberal Arts at Auburn University. Prior to this, I...

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