Two recently published articles may help explain why Democrats are more focused on income inequality than Republicans.

In the first article, Stephen Ohlemacher of the Associated Press, shows that Democrats represent most of the country's richest congressional districts (only two of the ten richest districts have Republican congressmen), but also a lot of poor districts.

That alone might lead us to draw a reasonable conclusion about the party leadership’s focus on income inequality: If their caucus is made up of members who disproportionately represent the poorest and richest districts, Democratic leaders—taking a bird’s-eye view of the party’s overall constituent base—might be quicker to recognize the yawning gap between the rich and poor than their Republican counterparts. The Democratic rank-and-file, comparing districts, could reason the same among themselves.

Furthermore, as Michael Zuckerman explains in his article ("The Polarized Partisan Geography of Inequality") in The Atlantic, it appears that Democrats also represent districts that are more unequal than Republican districts.  Using Gini indices computed by the U.S. Census Bureau, Zuckerman examines income inequality by congressional district and shows that, on average, both Democrats in Congress and their constituents tend to have more direct experience with income inequality than their Republican counterparts.  Income inequality would therefore be a more salient issue for Democrats than for Republicans, Zuckerman hypothesizes, which might help to explain why the parties are locked into polarized positions.

It’s not impossible to imagine this effect playing out in Congress. Given that [Democratic Representatives] Maloney (N.Y.-12) and Fattah (Pa.-02) regularly pass between some of the richest and poorest neighborhoods in America within a few minutes, it’s not shocking that they might see income inequality as a bigger problem than, say, Republican Representative Michele Bachmann (Minn.-06), a staunch conservative who (perhaps ironically) represents the district with the least income inequality in America (Gini index of 0.385). Likewise, it’s not impossible to imagine that Maloney’s and Fattah’s constituents—who look across the street at people with wildly different incomes than their own—think of income inequality as a bigger deal than Bachmann’s constituents do.

Read more:
http://www.denverpost.com/nationworld/ci_25420462/wealthiest-congressional-districts-represented-by-democrats
http://www.theatlantic.com/politics/archive/2014/04/the-polarized-partisan-geography-of-inequality/360130/#.U0Lw8nKD4MQ.facebook

TeachingwithData.org resources:
Wealth Inequality in America (http://www.teachingwithdata.org/resource/3922)
Social Class and Attitudes about Inequality: A Data-Driven Learning Guide (http://www.teachingwithdata.org/resource/3459)
Income Inequality in the U.S. (http://www.teachingwithdata.org/resource/3182)
Income Differences (http://www.teachingwithdata.org/resource/3113)