Why are Ocasio-Cortez, Omar, Pressley, and Talib estimated to be moderates by NOMINATE?

Jeff Lewis

August 05, 2019

In a previous post written last month, I explained why newly elected New York Congresswoman Alexandria Ocasio-Cortez is not estimated by NOMINATE to be among the most liberal members of the Democratic caucus. At that post, I focused on the votes that led NOMINATE to moderate her ideal point and, in particular, to locate Ocasio-Cortez at a much more moderate position that other progressive first termers such as Lauren Underwood, Rashida Tlaib, and Ilhan Omar. Since that time, new rollcalls taken on funding for the border crisis have pushed Tlaib, Omar, and Ayanna Pressley, who had previously been estimated to be among the most progressive Democrats, towards the location occupied by Ocasio-Cortez. Interestingly, Lauren Underwood’s estimated position has not shifted and remains among the very most liberal Democratic first termers as estimated by NOMINATE.

The logic driving these new placements exactly follows that described in the previous post and I refer the reader to that post for a more detailed explanation. Here I will simply highlight those new votes on which Ocasio-Cortez, Omar, Tlaib, and Pressley broke ranks with nearly every other member of Democratic caucus and voted with nearly every Republican. Those votes are interpreted by NOMINATE as conservative votes and NOMINATE adjusts those members’ locations to accommodate those votes accordingly. Over time, we expect those progressive members’ ideal points to drift back towards the left flank of their party as more votes that cleave all of the progressives from the rest of Democratic conference and the Republican conference are taken.

Liberal rankings of freshman Democrats in the 116th House

Here we see the first-dimension NOMINATE score ranking of freshman Democrats from most to least liberal as of August 05, 2019. Note that Underwood remains among the most liberal of the new class, but Omar, Pressley, and Tlaib are longer estimated to be among the most progressive as were in the previous post.

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, Omar, Pressley and Tlaib’s NOMINATE placements

The table below shows all of the votes on which Ocasio-Cortez, Omar, Pressley and Tlaib are predicted by NOMINATE to have less than a 40 percent chance (on average) of casting a vote on the side that they did and on which they all voted the same way. The table also shows the predicted probability of votes cast by Underwood on those same rollcalls (recall that Underwood is estimated to be second most liberal Democratic freshman). 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 average probability that NOMINATE attaches to their votes on each roll call. The most important of these votes for determining member’s locations is Roll Call 413 for which Ocasio-Cortez, Omar, Tlaib and Pressley were the only Democrats to defect from their Democrat colleagues and vote with all but three of members of the Republican caucus.

Underwood
Ocasio-Cortez/Omar/Pressley/Tlaib
Rollcall Bill Description Vote Prob. Votes Avg. Prob.
450 HR2500 On Agreeing to the Amendment Y 91.2 NNNN 22.8
72 HR840 On Agreeing to the Amendment Y 96.2 NNNN 18.3
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) Y 96.5 NNNN 20.5
346 HR2740 On Agreeing to the Amendment Y 98.3 NNNN 27.1
413 HR3401 Making emergency supplemental appropriations for the fiscal year ending September 30, 2019, and for other purposes (On Passage) Y 100.0 NNNN 23.5

To maximize the likelihood of these votes under NOMINATE’s spatial voting model, Ocasio-Cortez, Omar, Pressley, and Tlaib’s positions are shifted away from Underwood’s location and towards the locations of the Republican members. As described in the previous post, shifting their locations in this way does not substantially reduce the fit of the very large number of votes on which Ocasio-Cortez, Omar, Pressley and Tlaib sided with Underwood, but not moving them would greatly reduce the fit model for those few rollcalls on which they did not (such as Roll Call 413).