On March 22, Hillary Clinton won the Democratic primary in Arizona by a decisive margin (57 percent to 39 percent), but Bernie Sanders won both the Idaho and Utah caucuses by even wider margins (about 80-20 in each state).
How can it be that the Democrats are so split from state to state?
One answer is that Bernie Sanders does better in states that hold caucuses, and Hillary Clinton does better in states that hold primaries.
In all of the states that Sanders has won, seven of his 12 wins have been in caucuses, losing only three early caucuses to Clinton—Iowa, Nevada, and American Samoa .
On the other hand, Clinton has won 16 primaries, only losing five to Sanders—New Hampshire, Democrats Abroad, Vermont, Michigan, and Oklahoma.
Primaries are similar to voting in a general election. Votes are cast anonymously in booths and then the voters go home. Primaries also allow for early voting.
Caucuses are more convoluted, and supporters of candidates are split in a room and then argue for their particular candidate, trying to win over the crowd.
Caucuses are public and favor political activists, and primaries are quick and private events.
These two different methods of voting work to the strength of each candidate’s electorate, and the way it’s been quantified and discussed as an “enthusiasm gap.”
Sanders’s support comes predominantly from younger college-aged voters who are more likely to be politically active and willing to take a long time caucusing for their candidate.
Clinton’s supporters are older and more casual voters than Sanders, and might not be willing to spend a day caucusing, but are willing to stand in line for a voting booth.
Clinton also gets boosts from early voting, a function specific to primaries, which is aimed at allowing older voters to vote without forcing them go to the primary sites. This factored the most for the Arizona primaries, where most early and absentee voters were older.
Going forward in the Democratic primary calendar, Washington, Hawaii, and Alaska caucuses are set to take place this Saturday, March 26, and should favor Sanders.
However, a majority of states, especially the bigger states like New York, Pennsylvania, and California are all primaries and are likely to favor Clinton.