Source: C-SPAN

In the race for South Carolina’s 1st Congressional District — including large portions of Charleston — one of the key issues is incumbent Democrat Joe Cunningham’s record during his first two years in Congress. Both Cunningham and his opponent, Republican challenger Nancy Mace, have made competing claims about how to interpret Cunningham’s roll-call votes and bill sponsorship.

Incumbency is a double-edged sword. On the one hand, an incumbent’s record of accomplishment and ability to credit claim is one reason they win reelection at high rates. But, on the other hand, a lawmaker’s record is easy fodder for rivals. For example, the 2010 midterm showed that one vote (on the Affordable Care Act) can be the difference between winning and losing.

At the College of Charleston, I teach a class on the Congress, and my published work includes multiple peer-reviewed articles and one book on the legislative branch. In my view, there’s only one thing that’s clear in this debate: legislative behavior is complicated.

Let’s start with the most common claim: Cunningham votes with House Speaker Nancy Pelosi 90% of time. If you watch television, read the mail or spend time online, you may have seen an ad from Mace’s campaign making this claim.

In a TV ad, Mace compared Cunningham’s voting record to Speaker Nancy Pelosi | via YouTube

According to data compiled by ProPublica, an investigative journalism organization that tracks members of Congress, this claim checks out. It is indeed true. 

However, this statistic has one big caveat: By custom, the Speaker rarely votes on the House floor. In Pelosi’s case, she has refrained from voting on 91% of legislation in the current Congress. So, the 90% statistic is based on just 9% of all the votes cast.

Given the limited sample size, it is useful to add another point of comparison. Notably, there is another Joe in Congress representing South Carolina: Republican Joe Wilson of the 2nd District. According to the same dataset, Wilson has voted with Pelosi 30% of the time. Furthermore, on all roll-calls, Wilson voted with Cunningham nearly 40% of the time.

So, to summarize: Nancy claims Joe votes with the other Nancy 90% of the time, and though true, the other Nancy votes with the other Joe about 30% of the time, while Joe votes with the other Joe nearly 40% of the time. 

Like I said, it’s complicated.

A related issue is Cunningham’s ideology, with competing claims about whether Cunningham is “liberal,” “moderate” or something else entirely. Answering this question poses its own challenges.

For starters, people have very different definitions of ideology and there is little consensus on what counts as right- or left-leaning policy. Academic studies sidestep this problem by letting the data “speak for itself.” We simply assume lawmakers who vote together have similar ideologies and then use agreement scores to place all 435 representatives on a numerical scale. calculates this scale and makes the data publicly available. But these scores, valuable as they are, have their own limitations. 

First, even though lawmakers vote on hundreds of items in a two-year session, that number is tiny in comparison to the tens of thousands of policy items that could be voted on. Ultimately, the things that reach the floor tend to be the priorities of party leaders, a phenomenon that increases polarization in Congress.

Second, it is difficult to know what votes mean. We assume yes votes signal support for the policy under consideration, and that lawmakers who vote together agree with one another. But lawmakers often vote for a bill for strategic reasons (for example, to placate their constituents or due to pressure from party leaders) or against a bill they agree with because it doesn’t go far enough.

An illustrative example is U.S. Rep. Alexandria Ocasio-Cortez. On the one hand, Ocasio-Cortez votes with Republicans quite often. Yes, you read that right. Does this make her conservative? No, she votes with Republicans against legislation that she feels isn’t sufficiently liberal. At the same time, her signature policy proposal, the Green New Deal, has been bottled up by Democratic leaders.

Yet despite these limitations, roll-call scores are valuable pieces of evidence as to a member’s legislative behavior and underlying ideology.

According to, of the 236 Democrats to serve in the current 116th Congress, Cunningham ranks as the 233rd-most liberal. With a score of -0.13, where zero indicates a perfect moderate, there are only three Democrats to Cunningham’s right. 

How does Pelosi rank, according to these data? She is the 31st-most liberal Democrat, with a score of -0.49. Notably, Cunningham’s score is closer to five Republicans’ than it is to Pelosi’s.

Another way to measure the ideology of a member of Congress is to examine the bills they cosponsor. Unlike roll-call votes, members can sponsor and cosponsor legislation whenever they want — cosponsorship is not constrained by party leaders to the same extent.

According to data maintained by GovTrack, Cunningham has introduced 20 bills and cosponsored 211 in the current Congress. Using these data, GovTrack’s algorithm gives Cunningham a score of 0.45. On this scale, a score of 0.5 is a perfect moderate.

Interestingly, with a score of 0.45, Cunningham has the exact same rank as in the roll-call data — his cosponsorship record makes him the 233rd-most liberal Democrat in the House. One difference is that in the cosponsorship data, Cunningham is to the right of three Republican lawmakers who have slightly liberal cosponsorship patterns.

All in all, legislative behavior is a complex phenomenon, and no one metric can fully capture the complexity of a member’s record in Congress. All scores — voting with the Speaker, roll-call data and cosponsorship — contain limitations. When trying to evaluate a member’s record, voters should weigh multiple pieces of evidence. And on balance, two of the three measures reviewed above suggest Cunningham is a moderate Democrat. In fact, these two measures suggest he is as moderate as it gets.

Jordan Ragusa is an associate professor of political science at College of Charleston whose research has focused on legislative behavior in Congress.