It took all night to count all the votes in the Iowa Democratic caucus. Here's why.

Though Ted Cruz was declared the definitive victor in Monday night’s Iowa Republican caucus, Democratic officials scrambled through much of the night to declare a winner of their own.

That’s partially because the results in the Democratic caucus were so close — Hillary Clinton had 49.9 percent of the vote to Sanders’s 49.6 percent, a result that Clinton’s camp called a victory and Sanders's camp called a "virtual tie."

But part of the holdup was due to missing results from as many as 90 precincts, which Democratic Party officials scrambled to gather through the night. The missing results accounted for about 5 percent of the total vote.

By the time party officials announced the final tallies, results from only one precinct were still missing. But Sanders’s camp, frustrated by the disorganization, has still not formally conceded the race to Clinton.

Understaffed precincts probably caused the chaos

In Democratic caucuses, a person is typically designated ahead of time as a "temporary caucus chair" to run the event at each precinct. During the actual caucus, these temporary chairs are then often elected as permanent chairs, tasked with reporting the precinct’s official results back to the party.

As of Sunday morning, the Sanders campaign told the Des Moines Register that as many as 137 precincts had still not even been assigned temporary caucus chairs. The late scramble led officials from Sanders’s campaign to fret publicly that the temporary caucus chairs appointed late had not received adequate training, a scenario that could alter results in such a tight race.

The party denied that it had failed to staff its precincts ahead of time, but on Tuesday night it was asking the two campaigns to help track down the chairs that should have reported the missing results.

"We have reached out to the campaigns for help in contacting the chairs for our outstanding precincts," the party said in a statement. "We are not taking results from the campaigns. We are taking them from the chairs who are in these precincts."

Still, Sanders’s Iowa state director told Roll Call the request essentially amounted to asking the campaigns to report their results, a process he predicted would probably lead to "squabbles" on the outcomes.

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