It's no secret that the 2016 presidential nomination process left the Democrats divided. Supporters of Bernie Sanders and Hillary Clinton distrusted each other, questioned each other's motives, and, after the election was over, blamed each other for the party's loss. But was that divisiveness peculiar to 2016, or did it bleed over into subsequent elections? Some recent research of mine suggests that the Clinton/Sanders divide played out strongly in state-level Democratic primaries in 2017 and 2018.
My main approach was to examine campaign contributions to Democratic gubernatorial candidates in the 2017 and 2018 primaries. There were 33 Democratic gubernatorial primaries across the two years, excluding California (whose top-two system, in which everyone from both parties votes for the same slate of candidates, doesn't really provide for clean intraparty contests). The paper looks at patterns in the roughly 355,000 donations made to candidates in those races, and analyzes how those donors who also contributed to Democratic presidential candidates in 2016 broke down in their support for gubernatorial candidates.
In particular, I was interested in knowing what percent of Clinton and Sanders donors from 2016 backed the "party-preferred" candidate in the Democratic gubernatorial primary. The paper looks at those donors who'd contributed to both a Democratic gubernatorial primary candidate and to a state Democratic Party committee in 2017–18. There are only some 7,000 such donors, but their donation patterns tell us a good deal about how the party is leaning.
The study treats the candidate who received the plurality of donations from these candidate-and-committee donors as the party's choice in the contest. This turns out to be a pretty good indicator of success: in 27 of the 33 races, the party's choice won.
How did the donors from the 2016 presidential contest break down in terms of their support for the party-preferred candidates in the gubernatorial primaries? The table below shows the percentage of Sanders and Clinton supporters who backed the party's choice in the gubernatorial primary. Unsurprisingly, across all states, Clinton backers were more supportive of the party's choice than Sanders backers were, 69 to 53 percent.
The study also examines a subset of states where there was a divisive signal being sent by party elites. The rightmost column in the chart below evaluates the seven states—Iowa, Massachusetts, Michigan, Ohio, Oklahoma, Rhode Island, and Virginia—in which party donors clearly picked one gubernatorial candidate, while the Sanders-affiliated group Our Revolution endorsed another. And in those, donors were much more polarized, with 82 percent of Clinton backers supporting the party's choice and only 31 percent of Sanders backers doing so.
It's possible that Our Revolution was just picking races in which the party already seemed divided, and that they didn't cause much of this intraparty polarization. However, I examined that subset of races by date, looking both before and after the Our Revolution endorsement. Prior to the endorsement, 83 percent of Clinton backers and 42 percent of Sanders backers contributed to the party's choice in the gubernatorial primary. After the Our Revolution endorsement, that became 77 percent of Clinton backers versus 19 percent of Sanders backers, for a 17-point expansion of the gap between supporters. This suggests that the conflicting elite signals caused further polarization among party donors.
The study also examines the behavior of primary donors in the general election, analyzing whether people whose preferred candidate lost the primary election were less likely to donate to the party's nominee in the general election—and, even, whether they were more likely to donate to the other party's nominee.
As the table below shows, there was substantial polarization along these lines. Among those who donated to a Democratic gubernatorial primary candidate, 32 percent contributed to the nominee who their candidate lost the primary to, versus 48 percent who donated to their candidate if he or she won the primary. That difference was far more stark—19 versus 50 percent, respectively—in those states where the primary was divisive, as described above.
Although few Democratic primary donors contributed to the Republican nominee in the general election, they seemed more likely to do so, unsurprisingly, if their preferred candidate lost the primary. Only around 2 percent of donors to Democratic primary candidates contributed to the GOP candidate if their candidate won the primary, but 4 percent did so if their candidate lost.
The evidence in the paper suggests that there are still substantial divisions within the Democratic Party. This isn't to say that these divisions are stronger or weaker than they were in the past or that Sanders and Clinton created these divisions: further analysis of contributions in election cycles prior to 2016 would be needed to determine that. In all likelihood, the factions have been present in the party for a long time, although they may have been exacerbated in important ways by the 2016 contest.
What this research does show is that candidates and campaigns, whether at the national or state level, do not go into a nomination contest with a clean slate and get to decide how to position themselves. Important factions precede them and will determine to no small extent how that contest is shaped.