Why is Alexandria Ocasio-Cortez estimated to be a moderate by NOMINATE?

Jeff Lewis

August 05, 2019

Media coverage of newly elected New York Congresswoman Alexandria Ocasio-Cortez describes her as liberal or even “ultra-liberal” with good reason. For example, she supports the green new deal, reparations for slavery, and abolishing ICE — all positions associated with the left wing of the Democratic caucus. Curiously, more than 150 roll calls into the 116th Congress, her first-dimension NOMINATE score places her to the right of the majority of freshman Democrats. So, why does NOMINATE think Ocasio-Cortez is a moderate? This question is made all the more puzzling because NOMINATE ranks Lauren Underwood, Rashida Tlaib, and Ilhan Omar as the three most liberal of the new Democrats in the House which is consistent with the media coverage and public statements of those three members. In what follows, I identify the roll calls that pull Ocasio-Cortez’s NOMINATE location away from the locations of Underwood, Tlaib and Omar and explain why NOMINATE cannot, as yet, conclude that Ocasio-Cortez belongs among the left-wing members of the Democratic caucus.

As shown below, the reason is quite simple. Because there have been relatively few roll calls taken that divide the left wing of the Democratic caucus from the moderates, there have been few opportunities for freshman liberals to show their stripes. On the vast majority of votes, members located at Ocasio-Cortez’s moderate position and, for example, Omar’s liberal position are expected by NOMINATE to vote the same way. While there are votes on which Ocasio-Cortez joins other strong liberals in voting against the moderates in her party, there are a handful of votes on which Ocasio-Cortez has gone against nearly every other Democrat including Omar, Tlaib and Underwood and sided with (nearly) every Republican. While Congressional observers understand that votes like Ocasio-Cortez’s vote against the rules of the House are protest votes, NOMINATE does not. Rather, NOMINATE sees these as instances in which Ocasio-Cortez looks like a conservative and it adjusts her location to be more conservative accordingly.

In those cases in which a large number of liberal members join the Republicans in voting against the Democratic moderates, NOMINATE concludes that the vote did not strongly divide liberals and conservatives. Consequently, NOMINATE discounts those sorts of votes in determining members’ locations. However, when a member goes alone (or nearly so), in bucking her party, NOMINATE finds that to be highly informative about the member’s location (this is how NOMINATE is able to correctly infer that Susan Collins is a moderate). This is what leads Ocasio-Cortez to be placed in the middle.

Over time, we expect that the 116th Congress will hold more votes that sharply divide the progressive wing of the Democratic party from the Democratic moderates and Republicans, but until it does, Ocasio-Cortez’s willingness to protest alone will lead NOMINATE not to locate her among the Congress’s most liberal members.

Liberal rankings of freshman Democrats in the 116th House

Here we see that while most of the highest-profile new liberals in the Congress are at the top of NOMINATE’s ranking, Ocasio-Cortez is only estimated to be the 43rd most liberal of the 56 new Democrats.

Rank Member NOMINATE 1st Dimension
1 GARCIA, Sylvia (TX-29) -0.758
2 UNDERWOOD, Lauren (IL-14) -0.563
3 DEAN, Madeleine (PA-4) -0.538
4 GARCÍA, Jesús (IL-4) -0.537
5 TRAHAN, Lori (MA-3) -0.515
6 ESCOBAR, Veronica (TX-16) -0.487
7 LEVIN, Andy (MI-9) -0.438
8 NEGUSE, Joseph (CO-2) -0.428
9 PAPPAS, Chris (NH-1) -0.423
10 ALLRED, Colin (TX-32) -0.422
11 LEVIN, Mike (CA-49) -0.400
12 FLETCHER, Elizabeth (TX-7) -0.391
13 CISNEROS, Gil (CA-39) -0.388
14 HARDER, Josh (CA-10) -0.387
15 WEXTON, Jennifer (VA-10) -0.383
16 ROUDA, Harley (CA-48) -0.373
17 SHALALA, Donna (FL-27) -0.358
18 COX, TJ (CA-21) -0.354
19 MUCARSEL-POWELL, Debbie (FL-26) -0.349
20 SCHRIER, Kim (WA-8) -0.338
21 HOULAHAN, Christina (PA-6) -0.326
22 SLOTKIN, Elissa (MI-8) -0.322
23 STEVENS, Haley (MI-11) -0.322
24 HAYES, Jahana (CT-5) -0.319
25 TLAIB, Rashida (MI-13) -0.315
26 CASTEN, Sean (IL-6) -0.307
27 STANTON, Greg (AZ-9) -0.305
28 HILL, Katie (CA-25) -0.304
29 CRAIG, Angela (MN-2) -0.300
30 OMAR, Ilhan (MN-5) -0.299
31 HAALAND, Debra (NM-1) -0.288
32 LEE, Susie (NV-3) -0.286
33 PRESSLEY, Ayanna (MA-7) -0.283
34 KIM, Andy (NJ-3) -0.269
35 FINKENAUER, Abby (IA-1) -0.261
36 TRONE, David (MD-6) -0.255
37 MALINOWSKI, Tomaz (NJ-7) -0.247
38 CROW, Jason (CO-6) -0.245
39 PORTER, Katie (CA-45) -0.235
40 McBATH, Lucy (GA-6) -0.235
41 AXNE, Cynthia (IA-3) -0.232
42 PHILLIPS, Dean (MN-3) -0.232
43 OCASIO-CORTEZ, Alexandria (NY-14) -0.229
44 DAVIDS, Sharice (KS-3) -0.222
45 HORN, Kendra (OK-5) -0.201
46 SPANBERGER, Abigail (VA-7) -0.196
47 DELGADO, Antonio (NY-19) -0.181
48 GOLDEN, Jared (ME-2) -0.179
49 SHERRILL, Mikie (NJ-11) -0.179
50 LURIA, Elaine (VA-2) -0.159
51 VAN DREW, Jefferson (NJ-2) -0.155
52 ROSE, Max (NY-11) -0.155
53 TORRES SMALL, Xochitl (NM-2) -0.153
54 BRINDISI, Anthony (NY-22) -0.153
55 CUNNINGHAM, Joe (SC-1) -0.112
56 McADAMS, Ben (UT-4) -0.087
## Warning in rbind(names(probs), probs_f): number of columns of result is not
## a multiple of vector length (arg 1)
## Warning: 3 parsing failures.
## row # A tibble: 3 x 5 col      row col   expected actual file                                        expected    <int> <chr> <chr>    <chr>  <chr>                                       actual 1 192144 prob  a double N/A    'https://voteview.com/static/data/out/vote… file 2 196896 prob  a double N/A    'https://voteview.com/static/data/out/vote… row 3 214181 prob  a double N/A    'https://voteview.com/static/data/out/vote…

Votes that moderate Ocasio-Cortez’s NOMINATE placement

The table below shows all of the votes on which Ocasio-Cortez is predicted by NOMINATE to have less than a 40 percent chance of casting a vote on the side that she did. The roll call numbers shown in the first column are also clickable links to the pages for those votes on Voteview. The votes are sorted by the probability that NOMINATE attaches to Ocasio-Cortez’s vote on each roll call. These votes tell us just about all we need to know about why Ocasio-Cortez is estimated to be a moderate by NOMINATE.

For example, on rollcall number 48, Ocasio-Cortez was the only Democrat to vote “nay” and only ten Republicans voted “Yea.” On that vote, liberal members such as Underwood, Tlaib, and Omar are predicted to vote “Yea” with near (certainty). Even at Ocasio-Cortez’s moderate NOMINATE position, NOMINATE only gives her “Nay” vote a 1.8 percent chance. All of these votes illustrate instances in which Ocasio-Cortez broke from her party including at least some or all of its left-wing. In order to accommodate these maverick votes, NOMINATE adjusts her position to reflect that she has on several occasions cast votes that are (otherwise) strongly consistent with being a conservative.

Rollcall Bill Description Vote Prob. Votes Avg. Prob.
48 HR648 Consolidated Appropriations Act, 2019 (On Passage) N 0.8 YYY 99.7
45 HJRES28 Making further continuing appropriations for fiscal year 2019, and for other purposes (On Passage) N 1.9 YYY 99.4
50 HJRES31 Making further continuing appropriations for the Department of Homeland Security for fiscal year 2019, and for other purposes (On Passage) N 2.4 YYY 99.3
340 HR2740 On Agreeing to the Amendment N 5.9 NYY 38.4
228 NA On Approving the Journal N 6.6 YYY 87.2
57 HR769 Counterterrorism Advisory Board Act (On Motion to Suspend the Rules and Pass) N 17.4 NNY 30.7
6 HRES6 Adopting the Rules of the House of Representatives for the One Hundred Sixteenth Congress, and for other purposes (On Agreeing to Title I of the Resolution) N 17.8 YYY 92.0
72 HR840 On Agreeing to the Amendment N 18.2 NNY 32.0
86 HJRES31 Making further continuing appropriations for the Department of Homeland Security for fiscal year 2019, and for other purposes (On Agreeing to the Conference Report) N 21.2 NNY 34.0
450 HR2500 On Agreeing to the Amendment N 24.2 NNY 35.5
346 HR2740 On Agreeing to the Amendment N 30.4 NNY 40.1
413 HR3401 Making emergency supplemental appropriations for the fiscal year ending September 30, 2019, and for other purposes (On Passage) N 30.9 NNY 34.8
56 HR449 Pathways to Improving Homeland Security at the Local Level Act (On Motion to Suspend the Rules and Pass) N 32.5 YYY 82.3
269 HR2740 On Agreeing to the Amendment N 37.4 NYY 59.9

Few votes in the 116th House have divided liberal from moderate Democrats (through May 2019)

The following plot shows the probability that NOMINATE assigns to votes cast by Ocasio-Cortez against the average probability that it assigns to votes cast by Omar, Tlaib and Underwood on each rollcall in which Ocasio-Cortez, Omar, Tlaib, and Underwood all voted the same way. Here we see that on most of these votes, even with her moderate location, Ocasio-Cortez’s votes are well predicted by NOMINATE. Put another way, we find only a small number of votes for which moving Ocasio-Cortez to a similar location to Omar, Tlaib and Underwood would substantially increase the fit of Ocasio-Cortez’s votes. Thus, while her go-it-alone protest votes provide a strong impetus for NOMINATE to moderate Ocasio-Cortez’s location, the large number of votes on which she agrees with the other liberal Democrats provide little impetus for moving her position leftward.

Likelihood of Ocasio-Cortez’s votes by DW-NOMINATE position

Here we plot the likelihood (represented as the geometric mean probability of her vote choices) of Ocasio-Cortez’s votes being cast by a member located anywhere in the DW-NOMINATE space. Her actual estimated location, the one that maximizes the likelihood of her votes, is represented by the black dot. Note that the likelihood of her votes falls off rapidly as her location is shifted to the right while she can be moved along the edge of the space to the left with relatively less reduction in fit.