The recent Democratic Party debates have prompted pundits and prognosticators to wonder how far left the nominee can veer and still unseat President Trump in November 2020.

In a recent piece, David Leonhardt of the New York Times argued that instead of focusing on issues that expose Trump’s weaknesses, Democrats “have instead devoted substantial time to wonky subjects that excite some progressive activists -- and alienate most American voters.” Unexplored, however, is a basic question: Do Democratic voters actually want an intensely progressive candidate as their standard-bearer or would they prefer a more traditional moderate such as Joe Biden?

In order to get traction on this question, we turned to data from YouGov’s Sept. 9 poll. That survey explores respondents’ ideology and their strength of partisan affiliation. Combining the information from these questions allows us to paint a rough picture of the Democratic electorate. Table 1 presents the results of this exercise, summarizing the ideological distribution of Democrats given strength of partisanship.

Of all the respondents we label Democrats, 56% consider themselves to be “Strong Democrats” (and among them two-thirds say they are liberal) while 24% call themselves “Weak Democrats” and 20% think of themselves as independents who lean toward the Democratic Party (“Democratic-Leaning Independents or “Leaners”). In these latter two groups, approximately 60% are moderates or conservatives, a reminder that the party still contains substantial ideological diversity despite its liberal leanings.

As one might expect, these moderate and conservative Democrats tend to prefer Biden to either Sen. Bernie Sanders or Sen. Elizabeth Warren. Among moderate to conservative Strong Democrats, Biden leads his closest competitor by 25 percentage points; among Weak and Leaning Democrats of similar ideology he is ahead by 10 and 17 points, respectively (see Table 2).

Predictably, Warren and Sanders are more popular among progressives. Among liberal “Strong Democrats,” Warren holds a 19-point edge over Biden and an 18-point lead over Sanders; she also has a narrow advantage over her rivals among liberal “Weak Democrats.” Among independents who lean Democratic, Sanders has a plurality (which is fitting given his own loose association with the Democratic Party).

The current distribution of support benefits and burdens the candidates in different ways. On one hand, Warren and Sanders benefit from appealing to the liberal wing of the party, which contains 56% of all Democrats. If either of the two manages to elbow out the other and consolidate liberal support, this numerical superiority would provide an edge against Biden. On the other hand, neither Warren nor Sanders dominates among liberals the way Biden does among moderates and conservatives, which accounts for Biden’s current lead.

Biden also has the further advantage of being considered most likely to beat Trump, a perception that exists even among liberals. Seventy-three percent of liberal Democrats believe that Biden would defeat the current president; 71% and 58% believe the same about Warren and Sanders, respectively. Unsurprisingly, moderates and conservatives are even less confident in Warren’s and Sanders’ general election appeal. Only 54% of that cohort think Warren can win and a mere 50% say Sanders can win.

In summary, despite his frequent gaffes, Biden has maintained the public perception of his electability, a crucial asset when more than two-thirds of Democrats place beating Trump above having a nominee who agrees with their views.

It is worth noting, however, that the overtly ideological tenor of the current race suggests the eventual nominee will have to expend substantial effort to unite the party irrespective of who that person is. A significant percentage of Democrats ideologically aligned with their preferred nominee have expressed skepticism about the other potential standard-bearers. One-third of liberal Warren and Sanders supporters say they would be “disappointed” if Biden was the nominee and more than 40% of moderate/conservative Biden voters say the same about Warren and Sanders. While not an insurmountable obstacle, the nominee will likely have to neutralize this disappointment to win the White House.

David Brady is a professor of political science at Stanford University and the Davies Family Senior Fellow at the Hoover Institution.