DES MOINES, Iowa — Barack Obama didn't exactly get the response he was going for as he tried to energize his troops.

"We've been here a little over an hour," he told the crowd gathered at a town-hall stop in Sioux City, Iowa. "That's about how long it takes you to caucus."

"More like two hours!" a voice bellowed from the back of the room.

Yes, from the mouths of hecklers sometimes flows political truth. While each candidate faces a tough field of fellow hopefuls here in Iowa, they also face the challenge of engaging voters in a process a lot more complicated and time-consuming than walking into a booth and pulling a lever.

But if it's confusing to those born and raised in the Hawkeye State, then pity those of us who only turn our eyes here every four years. Fortunately, the folks at the Iowa Democratic Party have been kind enough to set up a caucus training session for the media (because, frankly, we can use all the help we can get).

The caucus process — this one-day affair that has commanded the attention of the men and woman who would be president for the past several months — is a strange political dance whose chief steps include debate, seat shuffling and more math than you might expect. Iowa got into the caucus business 160 years ago, and other than its move to the head of the candidate selection calendar in 1972, little has changed. "There's a tradition there," Norm Sterzenbach, political director for the Iowa Democratic Party, explained.

Republicans and Democrats handle their caucuses differently, but some key elements are constant on both sides of the aisle. Unlike a standard election where voters hit the polls when they choose, make their choices known and split, caucuses have a set start time and require a bit more work — discussing candidates, their party's platform and their local leaders. And it's all out in the open. You debate and discuss your preference with your fellow caucus participants, while any interested observers (reporters, bloggers, campaign staffers, interested students, anyone seeking shelter and warmth, etc.) look on.

Republicans opt for a simpler caucus process (perhaps something to keep in mind, undecided Iowa voters). For them, caucus day essentially boils down to a straw poll (not the straw poll, but a straw poll nonetheless). Votes are cast in secret (sometimes actually into a hat), the votes are counted and delegates are doled out later.

Democrats choose to make things a little more difficult (hence today's training). After a good deal of opening business (including the electing of officials and passing the hat for party funds), voters group themselves by candidate — all the Clinton folks stand over here, the Edwards people stand over there, the Kucinich people ... well, we'll cross that bridge when we come to it. After the initial sorting, each candidate's group then tries to poach additional voters from other groups. After about half an hour of that, the voters are counted again, and those candidates who don't have enough people in their group are not deemed "viable" (yup, that's it, those candidates are no longer in the running in Iowa).

"Basically, viability means they have a minimum number of supporters in the room to win a delegate," Sterzenbach explained. That minimum number is determined based on the first of many unique laws of caucus math, this one factoring in the number of caucus attendees and the number of delegates up for grabs.

Then the real fun starts. Voters who had been supporting the candidates now out of the running must join up with supporters for one of the remaining candidates. It's called "realignment," and it involves much wooing (but no favors, bribes or promises of yard work — "I think that's more urban legend than anything else," Sterzenbach said).

When the dust clears, the heads are counted and the real math comes in — delegates are distributed in proportion to the numbers supporting each candidate. This involves math worksheets, phone support from party officials and plenty of guidelines. "It's complicated," Sterzenbach deadpanned.

So complicated, in fact, that not everyone who starts the process hangs in there to finish it. "It happens quite a lot," Sterzenbach said. "Sometimes people just get sick of waiting around."

So why bother? Wouldn't it be easier to try the whole straight-up voting thing? "You don't get that social interaction in a primary," Sterzenbach said. "Caucuses are also better for the state political parties. When this thing is over, we've got a team of people who are very interested in this process and in their candidate."

It also guarantees that candidates aggressively work Iowa, hoping that consistent face time with voters leads to the type of deep connection required to draw someone into this process. So even as Sterzenbach does his best to explain the caucus to the bewildered media, throngs of campaign workers paper every inch of the street in front of this venue with campaign posters. In just a few hours, every major candidate in the Democratic race will be in this building, once again trying to convince voters that the debate, the realignment and the math are worth it.