1  Some Data

Objective data suggests that the leftiest candidates in the 2020 presidential race are Warren, Harris, Booker, and Sanders – in that order. Biden is in a precarious position, because he is not a lefty, not particularly progressive, and definitely not an Obama clone. Sanders is not nearly as far left as he is cracked up to be, although he is quite progressive on lifestyle and civil-rights issues.

The two-dimensional “dw-nominate” scores¹ are reliable, objective information – which is something you don’t see too often in the political world. Figure 1 displays US senator ideology in classic dw-nominate form, with a few enhancements.³

• I highlighted the 7 senators who are (or were) running for president in 2020.
• I also tacked on Joe Biden, who is also running, and who has well-established dw-nominate scores, since he used to be a senator.⁴
• Also, for comparison, I tacked on Barack Obama, who was a senator for a hot minute, and has a fairly well-known track record as president. Also Hillary Clinton, who served in the senate before becoming Secretary of State.⁴

Figure 1: US Senator Ideology Map

Here are the numbers for the top ten lefty senators. It is amusing to see that all 4 of the top 4 leftiest senators are running for president:

Along the same lines, here is the data for all 7 senators who are running for president (plus a couple of ringers):

• Faux News is howling about how Bernie Sanders is a socialist. Socialist! Socialist! Socialist! Soooohohohocialist! However, he is by no means the farthest left. OK, he is #4 (out of 100) on the list of leftiest senators, if you go by nom₁, but he is not as far left as Booker, much less Harris or Warren.

  He is quite progressive along the nom₂ axis, i.e. lifestyle and civil-rights issues, more so than anyone else who is running, even a bit more than Obama, as you can see in figure 1.

• Obama is pretty much a middle-of-the-herd Democrat, if you go by nom₁ alone. He is somewhat toward the progressive end of the scale along the nom₂ axis, i.e. lifestyle and civil-rights issues.
• The candidates who are ideologically closest to Obama, namely Klobuchar and Gillibrand, are getting virtually no traction in the primary, which is a bit odd, given Obama’s astronomical popularity. Politics is not logical.
• Biden is by no means a lefty. He is by no means an Obama clone. He is slightly to the right of Obama along the nom₁ axis. He is remarkably non-progressive when it comes to nom₂, i.e. lifestyle and civil-rights issues. Less progressive even than Bennet. It’s odd that Harris would be the one to call him out on this, since her nom₂ score is not very progressive.

  I do not understand why Biden currently has such a huge lead among Obama supporters in general and black voters in particular. I suspect this lead is very fragile. He’s been selling himself as an Obama clone, but people aren’t going to buy that forever.

2  Interpreting the Scores

Here is a simple way to think about the political meaning of dw-nominate scores: Primarily, a computer is used to fiddle with the points so that the final placement is a good predictor of how each legislator will vote.^{1, 2} The algorithm does not know or care about the political meaning of the votes, nor of any particular direction in the resulting plot. The objective at this stage is good prediction, not political meaning. In fact, at this stage the results are invariant with respect to all linear transformations, including rotations.

As a secondary postprocessing step, the results are rotated so that the horizontal axis corresponds to the conventional notion of partisanship. This is the only way in which humans inject political meaning into the process.

The meaning of the nom₂ score is not easy to explain. Perhaps the following will be of some use:

• For starters, we can note that by construction, it represents everything that has predictive or explanatory value but is orthogonal to raw partisanship; however, that’s not specific enough to be very useful.
• Secondly, we can get some handle on nom₂ by looking at the set of bills where Merkley and Wyden voted one way, while Manchin and Cortez Masto voted the other way. It should be straightforward to come up with such a list, but that’s more work than I feel like doing right now.
• Conventional wisdom asserts that nom₂ scores are somewhat associated with lifestyle and civil-liberties issues.

*   References

1.

Wikipedia article: “NOMINATE (scaling method)”
https://en.wikipedia.org/wiki/NOMINATE_(scaling_method)

2.

DW-Nominate interactive data viewer
https://voteview.com/congress/house
https://voteview.com/congress/senate

3.

I collected a bunch of data from disparate sources. I cleaned it up and made it available in a number of convenient forms, as described here:
www.av8n.com/politics/data-collection.htm

4.

The Obama and Biden dw-nominate scores are ten years old, but there is strong evidence that a person’s score tends to remain stable over long periods of time. Any change would be imperceptible and irrelevant for present purposes.