Unlike a traditional primary where voters go into a booth and cast a ballot, a caucus is a group effort — a group of registered voters in a room showing support for a particular candidate.
“Usually they like to have all the people who support Biden go over here, if you support Buttigieg go over to this corner – if you support Sanders or Warren – so you have all the groups try to gather together and they count up all the people that are there,” said Tim Hagle of the University of Iowa.
Each group backing a certain candidate has to make up 15 percent of all the attendees in the room for that contender to be considered “viable” to earn delegates.
“If you’re not viable then you have to reorganize and then it’s like OK, who his your second choice candidate? And then you have some negotiation that takes place and that’s where the campaigns talk to each other and they try to make deals that they say, ‘We’ll give you a delegate slot or vote you in as a delegate,’ or something of that nature,” Hagle said.
In Iowa, it may be important to have a “second choice” or a backup candidate who you might support during a second round of the caucus, if your favorite doesn’t meet that 15-percent threshold.
“The main goal among Democrats is to find someone who can beat Donald Trump,” Hagle said.
All the Democratic candidates are looking for a strong showing in the state that could lift them heading into later contests that will help decide the Democratic nomination.