Member joining patterns across party factions in the 115th Congress
By Danielle Thomsen
Two main teams compete for partisan control in the contemporary Congress, but even in the current context of high partisan polarization, differences between members of the same party remain. And when we look at the various factions within each partisan team, it is clear that some are more powerful than others. In the 1990s, for example, the Tuesday Group of moderate Republicans was an influential bloc on a range of issues. They worked behind the scenes to shape legislation on environmental protection, reproductive rights, and social welfare programs.
On the Democratic side, the Blue Dog coalition of moderates also had leverage on social and economic issues in the 1990s and early 2000s and often joined the Republicans to support tax cuts and defense spending. The moderates of yesterday were numerous and cohesive enough to influence the legislative agenda because they had the votes to sway outcomes. In recent years, however, the policy fortunes of the Tuesday Group and the Blue Dogs have decreased markedly. The internal balance of power has shifted away from the moderate factions in both parties.
How does the influence of party factions change over time? My recently published article in The Forum only begins to tackle this question by looking at which party caucuses newly elected members join. The joining patterns of incoming members provide a window into the current and future role of party factions in the policymaking process. I examined joining patterns in the 115th Congress to shed light on which factions are influential in Congress today.
On the Republican side, I focused on the Republican Study Committee (RSC), the House Freedom Caucus (HFC), the Republican Main Street Partnership (RMSP), and the Tuesday Group (TG). The Republican Study Committee was founded in 1973 and has historically been a conservative faction of the party. Now, the RSC is the largest Republican caucus, with 154 members (64 percent of the House Republican delegation). The House Freedom Caucus is the party’s most conservative faction today. Its roster is not publicly available, but the HFC is estimated to have between 35 and 40 members. The Republican Main Street Partnership (RMSP) was founded in 1994 and is a more moderate faction within the GOP, along with the Tuesday Group (TG). The RMSP has 74 members, and the TG is estimated to have between 40 and 50 members but it also has no official roster of members. The Tuesday Group is less powerful than the Freedom Caucus, in part because its members are less cohesive and less willing to withhold party support.
On the Democratic side, I looked at the Congressional Progressive Caucus (CPC), the New Democrat Coalition (NDC), and the Blue Dog Coalition (BDC). The Congressional Progressive Caucus is the most liberal faction, and at 75 members, is now the largest Democratic caucus. The New Democrat Coalition is to the right of the CPC, but its members are liberal on social issues. The NDC was founded in 1997, and although its membership has ebbed and flowed over time, it currently has a healthy 61 members. The Blue Dog Coalition is the most conservative faction, and its members are more conservative on economic and social issues. The Blue Dogs are the smallest Democratic faction, as they have suffered substantial losses in recent years. Its membership has shrunk to 18 members, down from more than 50 just four congresses ago.
There were 62 newly elected U.S. House members in the current 115th Congress, 34 Republicans and 28 Democrats. Of these, 10 did not join any of the seven caucuses described above; 30 joined one and 22 joined two. The breakdown of which factions newly elected members joined in the current 115th Congress is shown in the figure below.
Newly Elected Members Across Party Factions
On the Republican side, the majority of newly elected members joined the Republican Study Committee, which makes sense given that most Republicans who run for Congress today are ideologically conservative. Of the two main GOP factions, the RSC seems to be the fastest growing, with the RMSP trailing behind. The RSC added 23 to its ranks (68 percent of incoming Republicans), whereas the Republican Main Street Partnership added 13 (38 percent of incoming Republicans). Both the Freedom Caucus and the Tuesday Group attracted fewer incoming members than the other two Republican caucuses, though it is difficult to be certain since the rosters are not publicly available. The Freedom Caucus also has ambitions to grow its membership and invests more resources in candidate recruitment than the Tuesday Group.
On the Democratic side, the New Democrat Coalition added the most newly elected members to its ranks (14, or 50 percent of incoming Democrats), but the Congressional Progressive Caucus did not trail far behind (12, or 43 percent of incoming Democrats). The Blue Dog Coalition had a comparatively good year from an historical standpoint: 7 of the 28 newly elected Democrats joined the BDC (25 percent of incoming Democrats), and its membership increased from the previous Congress. Although the differences across caucuses are less stark on the Democratic side, it is nevertheless clear that the CPC and the NDC are more attractive options to incoming members than the Blue Dog Coalition. This is unsurprising given that most of the Democrats who run for Congress today are ideologically liberal.
What is also remarkable is how the percentage of incoming members who join the CPC has steadily grown over time. Following the 1992 elections, one year after its founding, 12 of the 65 incoming Democrats joined the CPC, or 18 percent of all incoming Democrats, compared to nearly half in the current 115th Congress.
The joining patterns of newly elected members have important implications for the current and future influence that factions can expect to have in the party and chamber. The changing fortunes of party factions in recent decades suggests that the shift away from the ideological center by the Republicans and Democrats is unlikely to slow down any time soon.
 The exact estimates for the Tuesday Group and the Freedom Caucus are unknown because membership lists are not available; these figures come from online reports based on statements to the media. Across dozens of reports and articles, there is substantial overlap in the individuals who are identified as members and the estimated size of the faction, which gives us additional confidence in these figures.
 As noted above, the exact estimates for the Tuesday Group and the Freedom Caucus are unknown because membership lists are not available; however, media coverage of both organizations references newly elected and veteran members alike.
Danielle Thomsen is an assisant professor in the Maxwell School of Citizenship and Public Affairs at Syracuse University.