Democratic presidential candidates hustled across the state yesterday on the eve of the Iowa caucuses, trying to fire up voters and appealing to those struggling with their choice in the crowded field.
Vermont Senator Bernie Sanders told several hundred supporters in a car park in Cedar Rapids a high turnout in Iowa would mean he wins and low turnout would result in the opposite. The event was moved outside after too many people showed up to fit into his nearby field office.
"We are the campaign of energy and excitement," Mr Sanders said. "We believe we are in a position to win tomorrow night" and that "gives us a path toward victory" over President Donald Trump.
Pete Buttigieg, the 38-year-old former mayor of South Bend, Indiana, talked up his newcomer status during a rally in Coralville, where a Republican asked why he should support Mr Buttigieg over former vice-president Joe Biden.
"I don't want to put too fine a point on it, but every single time my party has won the White House in the last 50 years, we have done it with someone who is new in national politics," Mr Buttigieg said.
In Dubuque, Mr Biden told voters there won't be time for a "on-the-job training" and pledged: "If you stand with me, we can end Donald Trump's reign of hatred and division and unify this country."
Massachusetts Senator Elizabeth Warren closed her Indianola event with an impassioned plea for her supporters to "fight back".
"Americans are at our best when we see a problem - we tackle it head-on and we fight it to the ground," Ms Warren said.
Underlying the frenzied late moments, campaigns and voters acknowledged a palpable sense of unpredictability and anxiety as Democrats begin selecting which candidate to send on to a November face-off with Mr Trump.
The Democratic race is unusually large and jumbled heading into today's caucus. Four candidates were locked in a fight for victory in Iowa; others were in position to pull off surprisingly strong finishes.
"This is going to go right down to the last second," said Symone Sanders, a senior adviser to Mr Biden.
Polls show Mr Biden in a close race in Iowa with Mr Sanders, Ms Warren and Mr Buttigieg. Minnesota Senator Amy Klobuchar and tech entrepreneur Andrew Yang are also competing aggressively in the state.
Democrats' deep disdain for Mr Trump has put many in the party on edge about the decision. A series of external forces has also heightened the sense of unpredictability in Iowa, including Mr Trump's impeachment trial in the Senate, which marooned Ms Warren, Mr Sanders and Ms Klobuchar in Washington for much of the past week.
Mr Biden's campaign appeared to be trying to lower Iowa expectations, cautioning against reading too much into today's results.
He is hoping to sustain enough enthusiasm and money coming out of Iowa to make it to more diverse states where he hopes to draw strong support from black voters. His campaign is particularly focused on South Carolina, the fourth state on the primary schedule.
"We view Iowa as the beginning, not the end," said Symone Sanders.
Mr Sanders, Ms Warren and Ms Klobuchar all fanned out across the state yesterday, trying to make up ground after missing most of the last two weeks of campaigning due to the Senate impeachment trial.
In a conference room in Cedar Rapids, Ms Klobuchar appealed to caucus-goers by asking them to think about the voters who won't be caucusing - moderate Republicans, voters who swung from Barack Obama to Trump and voters who stayed at home in 2016.
"They're watching all of this right now," Ms Klobuchar said. "We have people who want to come with us. And we need a candidate who is going to bring them with us instead of shutting them out."