In the context of lily-white Iowa and New Hampshire granting Bernie Sanders early life and a subsequent stream of southern states producing a near insurmountable delegate lead for Hillary Clinton, race has undoubtedly proved a defining element of the 2016 Democratic nomination fight. While Sanders has consistently gained more support from the white Democratic electorate, Clinton has won by even greater margins among black voters. That advantage may shrink soon, as exit polls have shown that black support for Sanders typically doubles or triples outside of the South, the area to which the race is moving–more Northeastern and Midwestern states remain on the Democratic calendar than Southern ones. At the same time, more Western states and thus more Hispanics will vote, representing a new electoral test for Bernie with a group that leans more heavily towards Clinton.
One of those challenges will arise when Arizona votes on March 22nd, a much more diverse state whose outcome will offer another indication if Sanders has any last-gasp chance for the Democratic nomination (even if he somehow wins, his path stays extremely narrow). Alongside the Grand Canyon State, two more states in Utah and Idaho, both of which favorable to Sanders due to the key racial component of this nomination race, will vote. Given this crucial demographic aspect, I will briefly review how these three impending contests will play out according to the state’s racial composition, and that of past state electorates.
Several racial variables can prove pertinent here: those relating to prior electorates–the share that whites, blacks, and Hispanics individually made up in electorates for states that have already voted (only for states with exit polls)–and those from Census data–the share that each of these three races makes up of the total population in all states.

Correlating all of these variables, which the above table shows, the relationship between Sanders’s share of the vote and black percentage of a state’s total population emerges as the strongest absolute one. This produces a very strong negative correlation of -0.88; the greater a black population lives in a state–not even its portion of the electorate–the lesser vote share it gives to Sanders. This strongest racial variable predictor can also be understood in the below plot.

Considering the low levels of black population–as expressed in the below table–in each of the three states imminently voting, this would seem to avail Sanders. Arizona contains the highest percentage at 4.7 of the three states, while the other two hover around one percent. In states with at least as small black populations that have already voted, Sanders has averaged 63.78 of the vote.

However, Hispanic/Latinos will now increasingly occupy a greater presence in state electorates, starting with the three Western states voting on Tuesday, and represent another demographic disadvantage for Sanders. Only five of the 26 states that have held Democratic elections contain a larger Hispanic population than these three new states. On average for these five states, the Clinton vote share has been 54.62–barely above her national average at 53.72, and thus indicating perhaps not as much of an advantage for her. At the same time, among the six states with the highest portions of Hispanics making up their state electorates (and with exit poll data available), Clinton has averaged 61.4.
As can be seen in the below plot, although most states that have voted had very low Hispanic portions of their electorates, those that had higher ones tended to vote less in favor of Sanders. At -0.14, the correlation is hardly strong however.

The idea of Clinton having a stronghold among Hispanic voters comes from robust support from them at the earliest stages of the primary race, as well as from national level polling and recent election results broken down by race. But on those last two points, ambiguity in past months has plagued the debate over which candidate claims greater support from Hispanics. It started with entrance polls for the Nevada caucus showing Bernie having won Hispanics by an eight-point margin, though that result was likely inaccurate for a variety of reasons. Then, the leadup to the Illinois primary–one of the more Hispanic-heavy states in the country–included wildly divergent levels of Hispanic support in different polls. Even in the past week or so, a polling firm in Morning Consult had Sanders leading among Hispanic voters by six points, and a few days later released a poll in which Clinton had an 11-point edge among the group. Earlier than that, YouGov had Clinton up eight points. In sum, there are clearly significant issues in polling the Hispanic population in the U.S. right now that likely have contributed to this lack of clarity.
However, the clearer indication of this group’s political leanings probably come from the states that have already voted. The below table shows the margin of victory for Clinton among Hispanics with large enough Hispanic populations:

Despite the suspiciously large positive margin for Sanders in Nevada, Clinton has still beaten him by an average of 17.25 percentage points among Hispanics through the four state contests with exit poll data on the subgroup. There’s plenty of variance in these numbers, however, and it seems the margin will grow smaller than the one in Texas or Florida; perhaps Sanders does better with all minorities outside the South, and not just with blacks as noted before. Nevertheless, it remains fairly clear that Clinton has a stable advantage among Hispanics in this race.
In order to estimate where Clinton and Sanders’s shares of the vote will fall in the three states voting on Tuesday, plotting their vote shares in previous states against the state population demographics of them–rather than their electorate demographics–is the best way to go about this; the already known state-wide racial compositions can then be used to see where the vote shares might fall.
The below plot of the Hispanic portion of a state and the vote share for Sanders reveals a very weak correlation of -0.08. Similar to what can be done and in conjunction with Graph 1 above in having the black percentage of the state population, however, knowing the Hispanic portion can indicate where Sanders’s vote share might more or less land.

Applying the demographic characteristics from Table 2 to Graphs 1 and 3, it seems that Bernie’s percentage vote share will fall in the low to mid 40s in Arizona, the high 50s to low 60s in Utah, and possibly in the high 50s but more likely in the 60s and even 70s range in Idaho. At the same time, the polling leading up to these contests points to a smaller lead for Sanders than these estimates, which likely rely too much on the smaller black populations across all three states and the smaller than average nonwhite populations in two of the three.