Via CNN:
The voter, once they begin the actual voting process, is then asked to rank either their candidates one to five in order of preference on a ballot.
That preference list is unique to caucuses and is done so that if the voter's top choice does not reach viability in their caucus site on caucus day -- that means they usually have 15% of the room supporting them -- their support can go to their second or third choice. Voters can express support for up to five choices in ranked order. For example, if a voter who voted early puts former Vice President Joe Biden as their top choice but Biden is not viable in their caucus site on Saturday, their second choice will be counted upon realignment.
Wouldn’t it be easier if all voters did this, not just early voters? Sure, let voters meet at caucus site, because a lot of them don’t make up their minds until talking to supporters of various candidates, then let them fill out a ranked ballot which allows their vote to be realigned if their first choice isn’t viable.
And you’d have paper ballots to fall back on if anything gets screwed up.