The House and Senate Votes on the Keystone XL Pipeline

Below we use Optimal Classification (OC) in R to plot the House’s 252-161 vote and the Senate’s 59-41 vote on approving the Keystone XL pipeline. The Senate fell one vote short of approving the measure, which was designed in part to help Senator Mary Landrieu’s (D-LA) prospects in her upcoming runoff against Rep. Bill Cassidy (R-LA).

31 House Democrats and 14 Senate Democrats joined with all voting Republicans in both chambers in support of the measure. The first dimension (representing legislators’ liberal-conservative positions) does a good job at capturing this internal divide among House and (especially) Senate Democrats. Three of the Democratic Senators who voted Yea were defeated in their re-election races earlier this month — Senators Mark Begich (D-AK), Kay Hagan (D-NC), and Mark Pryor (D-AR) — and these are among the more moderate members of the Senate Democratic Caucus. This helps to illustrate why polarization is likely to increase in the next (114th) Senate.

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Senate Polarization after the 2014 Elections

Though partisan polarization has increased dramatically in both chambers of Congress over recent decades, it has beenmore pronounced in the House than the Senate. There is reason to believe that yesterday’s midterm elections will narrow this gap, increasing the ideological distance between Democrats and Republicans in the 114th Senate.

Below we use DW-NOMINATE Common Space scores to plot the ideological positions of members of current, 113th Congress. We use Common Space scores because they allow for direct comparability between members of the House and Senate. The ideological distributions of Democrats and Republicans in the House are shown with the light blue and red lines, while Senate Democrats and Republicans are plotted using the dark blue and red lines.

We highlight the ideological locations of the nine Senate Democrats whose seats flipped (or are likely to flip) to Republicans: Senators Mark Begich (D-AK), Mark Pryor (D-AR), Mark Udall (D-CO), Tom Harkin (D-IA), Mary Landrieu (D-LA), Max Baucus (D-MT), Kay Hagan (D-NC), Tim Johnson (D-SD), and Jay Rockefeller (D-WV). We can also plot the positions of five of the Republican Senators-elect (or, in Louisiana, the front-runner for the December 6 runoff) who have served in the House and have comparable Common Space scores: Reps. Tom Cotton (R-AR), Cory Gardner (R-CO), Bill Cassidy (R-LA), Steve Daines (R-MT), and Shelley Moore Capito (R-WV).

The 2010 midterms devastated the ranks of moderate Blue Dogs in the House. To a lesser degree, the 2014 midterms will have a similar effect on the Senate Democratic Caucus. Six of the Democratic Senators shown are among the seventeen most moderate Democrats in the current, 113th Senate (using the Common Space scores). With the exception of Senator-elect Shelley Moore Capito (R-WV), their replacements do not appear to be symmetrically moderate. The other four Republican Senators-elect for whom we do not have ideological scores (Dan Sullivan in Alaska, Joni Ernst in Iowa, Thom Tillis in North Carolina, and Mike Rounds in South Dakota, seem likely to be at least as conservative as the median member of their party’s caucus). Indeed, the freshman Republicans in the 114th Senate appear primed to move their party’s distribution closer to that of House Republicans.

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The House and Senate Votes to Approve Obama’s Request to Arm and Train Syrian Rebels

Below we use Optimal Classification (OC) in R to plot the House’s 273-156 vote and the Senate’s 78-22 vote to approve President Obama’s request to arm and train Syrian rebels. As seen below, both votes split the parties, with 85 Democrats/71 Republicans in the House and 10 Democrats/12 Republicans in the Senate voting Nay.

There are not clear liberal-conservative divides within the parties in the House, but the second dimension (on the vertical axis) appears to do a better job at classifying Yea and Nay votes. Although the substantive meaning of this dimension is not entirely clear in the contemporary Congress, we have previously suggested that it may represent an insider vs. outsider divide. On the Senate vote, however, there are clearer ideological splits (especially in the Republican Party), with more conservative Republicans and more liberal Democrats being more likely to oppose the resolution. We saw a similar pattern in Senators’ announced positions on Syria last year.

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Evidence of Assymetric Polarization in Congress with Common Space Scores

There is little question that the parties in Congress have moved ideologically further apart over recent decades. But has polarization been symmetric (with both parties moving away from the center at roughly equal rates), or has it been assymetric (driven more by Republican than Democratic movement)? DW-NOMINATE scores unambigously support the claim of asymmetric polarization, but some alternate ideological measures suggest that polarization has been more symmetric.

Below we use Common Space DW-NOMINATE scores to demonstrate that the finding of asymmetric polarization is not an artifact of the time trend allowed in regular DW-NOMINATE scores. With Common Space scores, a single score is estimated for each member based on their entire (often decades-long) congressional roll call voting record. Separate scores are not estimated for each member in each Congress. Hence, the only factor that could be driving polarization in the graphs below is member replacement (for instance, when a more conservative/liberal Senator replaces a more moderate Republican/Democrat).

The 10%/90% ranges refer to the 10th and 90th ideological percentiles of Democrats and Republicans in both chambers. That is, 80% of Democrats and Republicans in the corresponding chamber fall within these bands. We see the same polarizing trends as when using standard DW-NOMINATE scores: the House has polarized more than the Senate, and Republicans have moved further away from the center than Democrats. The final graph below shows a histogram of the House and Senate distributions in the current 113th Congress, with the positions of some key past and present figures denoted. There is a clear hump on the right that is comprised of mostly new members of Congress like Senators Ted Cruz (R-TX) and Rand Paul (R-KY).

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The Senate Vote to Invoke Cloture on the Campaign Finance Amendment and the House Vote to Condemn the Taliban Prisoner Swap

Below we use Optimal Classification (OC) in R to plot the Senate’s 79-18 vote to end debate on a constitutional amendment to protect campaign finance regulations and the House’s 249-163 vote on a resolution condemning the Obama administration for not notifying Congress about the deal to exchange Taliban prisoners for Sgt. Bergdahl last June.

As seen below, the Senate vote splits Republicans and the House vote splits Democrats, both along ideological lines. The group of 18 Republicans who opposed cloture included conservative Senators like Ted Cruz (R-TX) and Rand Paul (R-TX), while the 22 House Democrats who supported the prisoner swap resolution included Blue Dogs like Reps. John Barrow (D-GA) and Jim Matheson (D-UT) as well as Senate hopefuls Reps. Bruce Braley (D-IA) and Gary Peters (D-MI). Both Braley and Peters are classification errors: on the basis of their ideological positions, the model incorrectly predicts them as Nay votes.

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House: Two Immigration Votes

Below we use Optimal Classification (OC) in R to plot the House’s two recent votes on immigration: its 223-189 vote on a$694 million appropriations bill to enact new security measures along the U.S.-Mexico border and its 216-192 vote to end the Deferred Actions for Childhood Arrivals (DACA) program. Both votes were party-line, with the exception of four Republicans and one Democrat on the border funding bill and 11 Republicans and 4 Democrats on the bill to end DACA.

Particularly on the bill to prohibit the president’s use of DACA to stop deportations, ideology appears to do a good job of capturing the handful of party crossovers. The four Yea Democrats (Reps. Barrow, McIntyre, Peterson, and Rahall) are among the most moderate House Democrats and OC correctly predicts two of these (Barrow and McIntyre) as Yea votes. The eleven Nay Republicans (Reps. Amodei, Coffman, Denham, Diaz-Balart, Gardner, Heck, Kinzinger, Reichert, Ros-Lehtinen, Valadao, and Upton) generally represent districts with larger Hispanic populations but are also in the moderate wing of the House Republican caucus.

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Note: The plots show only 222 and 215 Yea votes, respectively, because newly-elected Rep. Curt Clawson (R-FL) voted Yea on both measures but has not yet cast enough votes to be included in the scaling.

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The 50th Anniversary of the Civil Rights Act: Plotting the House and Senate Votes

Today marks the 50th anniversary of the enactment of the Civil Rights Act. The Civil Rights Act passed the House in a 290-130 vote and the Senate in a 73-27 vote. Below we use DW-NOMINATE scores to plot both votes. First dimension DW-NOMINATE scores represent legislators’ ideological positions along the liberal-conservative spectrum and, during this period (as well as throughout the mid-twentieth century), the second dimension captures regional differences among members of Congress. Regional divides were most apparent on votes involving race and civil rights issues.

Accordingly, the divide on both of these votes separating predicted “Yeas” from predicted “Nays” runs mostly along the second (regional) dimension. Most Southern Democrats (with high second dimension scores) voted against the bill in both chambers and were joined by a handful of mostly conservative Republicans (like Senator Barry Goldwater [R-AZ]). But both votes far more reflected regional differences than ideological ones.

In the half-century since passage of the Civil Rights Act, the second regional dimension has all but disappeared in congressional voting. Racial issues have become questions of redistribution (a fundamental liberal-conservative disagreement), and social/cultural issues like gun control and abortion have also folded into the liberal-conservative dimension. To illustrate this, in the final image we show how well one and two-dimensional models classify congressional voting on the issues of abortion, gay rights, gun control, and immigration. The measure of classification is the APRE (Aggregate Proportional Reduction in Error), and measures how much improvement the model offers in classification of legislators’ votes. The maximum APRE is 1 (complete improvement), while a value of 0 indicates no improvement over the null model. As can be seen, the fit of all four issues to a one-dimensional ideological (liberal-conservative) model has steadily climbed to nearly 1 over recent decades. Both racial and social/cultural issues are now largely encompassed by the primary liberal-conservative dimension.

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How Conservative is Eric Cantor?

Tonight comes the surprising news of House Majority Leader Eric Cantor’s (R-VA) primary upset by a Tea Party challenger. Just how conservative (or not) is Rep. Cantor? Using DW-NOMINATE Common Space scores (which measure the ideological positions of Members of Congress based on the entirety of their roll call voting records), we find that Cantor is more conservative than 61% of Republicans in the (current) 113th House and more conservative than 76% of Republicans in the 113th Senate.

Though already a sound conservative in the current Congress, Rep. Cantor would have been among the most conservative Republicans (more conservative than 83% of Republicans) 20 years ago in the 104th House. Below we plot the ideological distribution of Republican members of the 104th House (in light red) and of the 113th House (in dark red). We also mark the locations of the top three Republican leaders (the Speaker, Leader, and Whip) in both Congresses. Not only is Rep. Cantor the most conservative of the top three Republican leaders in the current House (Speaker John Boehner and Whip Kevin McCarthy), but is also more conservative than former Speaker Newt Gingrich.

It is also noteworthy that the current House Republican leadership is to further to the left of the rest of the party than was the case in the 104th House.

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House: Vote to Prohibit Funds for DEA Raids on State-Legalized Medical Marijuana

Below we use Optimal Classification (OC) in R to plot the House’s 219-189 vote to prohibit funds for DEA raids on medical marijuana operations in states that have legalized it.

Contrary to the narrative that it was mostly moderate Republicans who comprised the 49 GOP votes in favor of the amendment (sponsored by Rep. Dana Rohrabacher (R-CA)), the plot below shows that the Republican Yea votes are fairly even distributed along the first dimension (representing liberal-conservative position). The difference in the mean first dimension scores of House Republicans who voted Yea and Nay is negligible (0.01) and not statistically significant (p = 0.43). In part this could be because the proposal also touches on states’ rights, which may have earned it the support of even socially conservative House Republicans like Reps. Paul Broun (R-GA) and Mo Brooks (R-AL). Indeed, the second dimension appears to do a better job of dividing House Republicans than the first dimension, with libertarian-minded Republicans like Reps. Justin Amash (R-MI) and Walter Jones (R-NC) supporting the amendment and holding very high (indeed, the two highest) second dimension scores.

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House: Vote to Limit NSA Phone Surveillance

Below we use Optimal Classification (OC) in R to plot the House’s 303-121 vote to limit the National Security Agency’s controversial phone surveillance program.

As the plot below shows, there is almost no ideological organization to this vote. It would be plausible to expect that this would be a “two-ends-against-the-middle” vote; that is, that the most liberal Democrats and the most conservative Republicans would spearhead support for this measure. But, to the extent that there is an ideological pattern on this vote, it supports the opposite conclusion. The mean first dimension coordinates of Democrats voting Yea is -0.46, while the mean scores of Nay Democrats is a slightly more liberal -0.52. The most conservative House Republicans were also more likely to vote Nay, with the mean first dimension score of Yea Republicans at 0.40 and of Nay Republicans at 0.44. Of course, these differences are minor.

The cutting line (dividing predicted Yeas from predicted Nays) runs along the second dimension. But, complicating matters more, those with high second dimension scores (legislators like Rep. Justin Amash (R-MI) and Walter Jones (R-NC)) are predicted to vote Nay, even though they have been among the most vocal critics of the NSA. Many of these legislators voted Nay because the bill did not go far enough to rein in NSA surveillance programs. Because of this, it is difficult to attribute substantive meaning to the second dimension on this vote.

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