click to enlarge Paul Heintz

Sen. Bernie Sanders (I-Vt.) addressing supporters Sunday in Cedar Rapids, Iowa

click to enlarge Paul Heintz

Supporters of Sen. Bernie Sanders watching him speak outside his field office in Cedar Rapids, Iowa

click to enlarge Paul Heintz

Sen. Bernie Sanders embracing national campaign cochair Nina Turner in Cedar Rapids, Iowa

click to enlarge Paul Heintz

Sen. Bernie Sanders addressing supporters at his field office in Newton, Iowa

When Sen. Bernie Sanders (I-Vt.) arrived at his Cedar Rapids field office Sunday morning, he marveled at the crowd of volunteers who had gathered in a parking lot to hear him speak."We even have people up on the snowbank!" Sanders exclaimed, gesturing toward a small group of sign-wielding hipsters assembled atop a dirty pile of snow. "Whoa!"On his final day in Iowa before Monday's Democratic presidential caucuses, Sanders made his way from Cedar Rapids to Des Moines, dropping by field offices to thank his loyal foot soldiers and encourage them to keep at it."The message is that we cannot simply complain about the status quo," he told the crowd in Cedar Rapids. It was not the time, he said, to complain about President Donald Trump or low wages or the high cost of prescription drugs. "Now is the time to end the complaining," he said. "Now is the time for action. Action is tomorrow night."Whether that action would result in victory was anything but clear on Sunday.Though recent polls have shown Sanders holding a slight lead in the state , three competitors have been nipping at his heels: former vice president Joe Biden, Sen. Elizabeth Warren (D-Mass.) and former mayor Pete Buttigieg of South Bend, Ind. Adding to the uncertainty, a much-anticipated poll conducted for thewas spiked Saturday night after an error was discovered, depriving political observers of a key caucus indicator.But the Sanders supporters gathered at the Cedar Rapids office weren't waiting for a poll to tell them what might happen."I think he's gonna win the nomination," said Boyd Walker, a real estate investor from Alexandria, Va., who traveled to Iowa last Thursday to volunteer. "He's gonna win Iowa. He's definitely gonna win New Hampshire. And whoever wins those two is gonna become the nominee. You can see the excitement on the ground."That excitement was palpable in Iowa City, where Sanders addressed an overflow crowd in another strip mall parking lot before entering a jam-packed field office. "You would not believe the kinds of turnout that we're seeing," he told the assembled volunteers.The scene was similar that afternoon at Sanders' Newton field office. There, he told supporters that he planned to return to Washington, D.C., later that night to again take part in Trump's impeachment trial. He said he would come back to Iowa on Monday night to await the results of the caucuses.Sanders took the opportunity to reflect on what he said had been "a long campaign" in Iowa. "We have done well over a hundred town meetings and rallies," he said. "We have spoken to tens of thousands of people. And we have put together, I think, an unprecendently strong grassroots movement."The candidate thanked Iowans for their hospitality and "their seriousness of purpose." He added, "I think the people of this state get it — that in the most consequential election in the modern history of America that they go first tomorrow night."Later Sunday afternoon, Sanders concluded his Iowa campaign with a brief stop at a campaign Super Bowl party at a Des Moines bar. As staffers and volunteers munched on chicken wings and hoisted beers, the candidate made one final speech."Tomorrow night is the beginning. It is the beginning of the end for Donald Trump," he said. "It is the beginning of the moment when we tell the billionaire class and the 1 percent, 'This country belongs to all of us, not just the few.'"