The Note: Iowa caucuses pose huge questions for Biden, Bernie

The TAKE with Rick Klein

It could be photo finish in Iowa -- one where candidates are taking pictures of slightly different races.

Little is settled going into Monday night’s Iowa caucuses, and little is likely to be settled by the results. Democrats see a dizzying array of potential outcomes, with four-plus candidates in the delegate mix even as consensus among campaigns has settled on Iowa suddenly being Sen. Bernie Sanders' to lose.

Iowa will serve as the first, and perhaps most important, test of competing theories of what the Democratic Party needs to win. Sanders' view of progressive mobilization goes up against former Vice President Joe Biden’s take on pragmatic electability -- with the other major candidates coming at voters from different angles of their own.

"We are the campaign of excitement and energy," Sanders told supporters at one of his last rallies on Sunday.

"It’s not enough to make promises," Biden said at one of his final events in the state. "You have to keep them."

This segment of the showdown leaves their rivals -- including Sens. Elizabeth Warren and Amy Klobuchar and former South Bend, Indiana, Mayor Pete Buttigieg -- on the outside looking in, with former Mayor Michael Bloomberg looming at the end of this first month of voting.

Warren, Buttigieg, Klobuchar and Andrew Yang have chances to muscle into the campaign conversation based on Iowa, which has already served to thin a historically large field.

But even as Democrats start to see answers to some of their biggest questions, even bigger questions will be raised. The difference between a Sanders win and a Biden win would point the party in much different directions, as would an upset from any of the other contenders.

The Iowa caucuses

The RUNDOWN with MaryAlice Parks

Sen. Bernie Sanders' team played the long game.

After 2016, some of his top advisers leaned into the Democratic Party and insisted on changes to rules and reporting that could impact the way voters see the results Monday night.

There is only one way to win in Iowa. Voters at caucuses pick delegates who go on to vote for candidates at the national convention. Delegates are the prize.

Still, some candidates, like Sanders, could celebrate other numbers. For the first time, the state party will tell the country who voters picked when they first walked in.

Remember, in Iowa, it is common for people to go in with a list and move on to a second choice if their first pick doesn't have enough support to advance in the room.

That change could give some campaigns talking points they like. If, for example, someone just barely qualifies for a delegate, but still comes in fourth in that first popular vote, it could look good. Or, if someone does not get a delegate at all, but has numbers that surprise pollsters, they could tout that as well.

The consequences of Iowa are as much about headlines, storylines and momentum as delegates.

The TIP with Kendall Karson

Their bets have been placed, and now the presidential hopefuls are banking on turnout to cash in on Monday's marquee contest.

In such a competitive primary and with the urgency to oust President Donald Trump fueling Democrats' enthusiasm, the state Democratic Party is preparing for historic turnout. Expectations are that 2020 could surpass 2008's record of more than 239,000 caucus-goers showing up for the hours-long event.

But it isn't just about how many people show up, it's also where. Sen. Bernie Sanders' bet on the youth vote means he'll need high turnout in Johnson and Story counties -- home to the University of Iowa and Iowa State University. With Biden relying on blue collar voters in more rural parts of the state, look to Black Hawk and Scott counties in the east, and Sioux County in the west. And for Sen. Elizabeth Warren and former Mayor Pete Buttigieg, who need an Obama-style finish to answer questions on electability, the white-collar suburbs outside of Des Moines, Cedar Rapids and other cities could bring a much-needed breakout night.

"We need a very strong finish here in Iowa because this is our chance to show versus tell that we’re building the organization that can turn people out and go on to defeat Donald Trump," Buttigieg said in Coralville, a suburb of Iowa City.

THE PLAYLIST

ABC News' "Start Here" Podcast. Monday morning’s special edition of "Start Here" comes from Iowa ahead of the caucuses Monday night. ABC News’ Iowa campaign reporter Sam Sergi takes us around the state to show us how the process works, how this year is different than 2016 and what voters are thinking ahead of the big night. http://apple.co/2HPocUL

ONE MORE THING

The Iowa caucuses, which have been the first nominating contest in the country since 1972, mark the official start of the presidential election season -- giving the Hawkeye State an outsize influence over the primary race. Here's how they work.

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