In February of 2009, second-term congressman Bruce Braley of Iowa announced the formation of a new Congressional Member Organization, the Populist Caucus. Braley set out six central issues for the caucus:
The caucus aims to bring members of Congress together by rallying around six key middle class economic issues:In January 2010, Braley's office confirmed that the Populist Caucus has grown from an initial 23 members to a full 30. Who are these members of the Populist Caucus? How do they interact with one another? Has the Populist Caucus' success in attracting new members within the House translated to legislative success? How thoroughly have members supported policies in line with the platform of the Populist Caucus as noted above? To answer these questions, That's My Congress delves into the congressional record of cosponsorship for both the broad set of 4,412 substantive "H.R." bills introduced to the House of Representatives during the year of 2009, bills specifically promoted by the Populist Caucus, and bills consistent with the Populist Caucus platform but not mentioned in caucus communications. Which members of the Populist Caucus have built the strongest cooperative relationships with one another? Which members of the Populist Caucus are most and least likely to lend their support to caucus-endorsed bills? Which Populist Caucus members are most likely to carry their populist principles beyond official caucus business to the promotion of bills that follow the populist spirit even if they are not endorsed by a caucus letter?1. Creating Good Jobs and a Secure Retirement: Creating and retaining good-paying jobs in America, providing fair wages, proper benefits, a level playing field at the negotiating table, and ensuring American workers have secure, solvent retirement plans;
2. Cutting Taxes for the Middle Class: Cutting taxes for the middle class and establishing an equitable tax structure;
3. Affordable Healthcare: Providing affordable, accessible, quality health care for all Americans;
4. Quality, Affordable Education: Ensuring quality primary education for all American children, and affordable college education for all who want it;
5. Fair Trade: Defending American competitiveness by fighting for fair trade principles;
6. Protecting Consumers: Protecting consumers, so that Americans can have faith in the safety and effectiveness of the products they purchase.
Introducing a bill to the House of Representatives is a necessary step in getting it passed, but it's not enough. Some members of the Populist Caucus are more popular than others; their bills gain more support (through the act of cosponsorship) than other members' bills. Turning the tables, some members of the Populist Caucus are more prolific cosponsors than others, lending their support more readily. The graph below color-codes members of the Populist Caucus by what we term the "Balance of Cosponsorship". The Balance of Cosponsorship for a caucus member is the # of cosponsorships his/her bills gain from other caucus members, minus the # of cosponsorships s/he gives to other members' bills. The Balance of Cosponsorship is positive (colored green) when a caucus member gets more cosponsorships than s/he gives and is negative (colored red) when a caucus member gives away more cosponsorships to others than s/he gets in return.

Also on display in the above graph are are arrows pointing from one Representative to a second Representative. These arrows are present when the first Representative has cosponsored at least 5 of the bills introduced by the second Representative. These are indications of strong ties in the Populist Caucus, and the pattern of these ties indicate the presence not only of central figures to the caucus (most strikingly Bob Filner and Peter DeFazio), but also the existence of factions within the Populist caucus. These caucus factions are subgroups focused on shared support from a caucus member (four women: Janice Schakowsky to Linda Sanchez, Jackie Speier and Louise Slaughter), shared support to a caucus member (three men: Hank Johnson and John Yarmuth to Lloyd Doggett), or reciprocal ties (Iowa-based triad Leonard Boswell, David Loebsack and Bruce Braley).
You might think that the Balance of Cosponsorship could be easily predicted by paying attention to the number of bills a caucus member has introduced. Members who introduce a lot of bills have more opportunities to pick up cosponsors -- but such members also tend to be more active cosponsors of others' legislation, an indication of their overall greater engagement. A scatterplot of the number of bills introduced ("sponsored") by a member by their Balance of Cosponsorship shows a mild relationship at best, with an R-squared statistic indicating that only 20% of the variation in the Balance of Cosponsorship is due to the number of bills a member has sponsored. When the two outliers in the caucus -- poor producer, poorly supported Eric Massa and richly productive, strongly supported Bob Filner -- are eliminated from consideration, there is essentially no correlation between the two variables.
