AMES, Iowa — A frenetic year of campaigning in Iowa came to a close on Sunday as the Democratic presidential candidates made their final pitches to a party electorate that’s desperate to take down President Trump.

And responding to the anxiety of Democrats in the state holding the first-in-the-nation caucuses Monday night, the candidates each lingered on the same simple point: I can win.

“Our number one job is to beat President Trump,’’ said Senator Elizabeth Warren, directly referencing concerns about gender and electability in her final town hall event. “Women win,’’ she told the crowd of 500 in a wood-paneled hall at Iowa State University in Ames, “let’s get this done.’’

As much as this campaign has been about lofty ideas — former vice president Joe Biden’s call to “restore the soul of our nation,’’ or Vermont Senator Bernie Sanders’ call for a political revolution — the candidates crisscrossed the state on Sunday to complete their campaigns right where they began: with the party’s all-consuming need to knock Trump out of office.

“I am really anxious. I’ve been reluctant to give him any nicknames. But I do have a nickname I want to give him — former president Trump,’’ Biden told a crowd of 500 in Dubuque.

Biden’s perceived strength as the most electable Democrat has carried him through some uneven debate performances, and he took his last opportunity to boost those credentials before he faces his first real test on Monday night.

“Republicans and Trump don’t want me because they know I’m going to beat him if I’m your nominee,’’ he said.

In Coralville, Pete Buttigieg told some 900 supporters he could bring progressives, moderates, and even Republicans into the Democratic fold. And on Saturday night in Cedar Rapids, even Sanders and his surrogates repeatedly stressed the 78-year-old’s ability to win, a focus that at times displaced parts of his usually policy-heavy stump speech.

“We’re going to win because we are the campaign of energy and excitement,’’ Sanders told the arena of mostly young fans, taking the stage after the filmmaker Michael Moore introduced the senator by rattling off a list of head-to-head polls showing Sanders beating Trump.

On Sunday, Sanders appeared to be in a good mood as he visited several campaign offices to rally and thank his volunteers ahead of caucus day.

“Let us tomorrow night have the largest Iowa caucus voter turnout in the history of this nation,’’ he told his supporters at a packed campaign office in Newton. His surrogates confidently predicted victory. “Baby, we will win the great state of Iowa,’’ former Ohio state senator Nina Turner told the crowd.

The weekend brought a fresh burst of activity to Iowa after Warren, Sanders, and Minnesota Senator Amy Klobuchar spent the week stuck in Washington for Trump’s impeachment trial, relying on their surrogates to make the case in their stead.

Their race is fluid, with four candidates — Sanders, Warren, Biden, and Buttigieg — bunched near the top. A poll expected Saturday night from the Des Moines Register and CNN was abruptly shelved, denying voters and observers one last window into the ever-shifting dynamics of the race.

As they dashed around the state, the candidates’ messages sometimes seemed to run together. Biden and Warren touted “hope over fear’’ — him in a campaign speech on Sunday, Warren on signs she distributed to supporters over the weekend. Warren and Buttigieg stressed the need for unity. And everyone noted the time for Iowans to decide had arrived.

“The danger is real, our democracy hangs in the balance,’’ said Warren in Ames. “At this moment, you will decide here in Iowa, what do we do? Do we go back, do we cower, do we take the timid approach? Or do we fight back?’’

Warren spent much of the weekend honing a pitch that she is the candidate best equipped to unite the different factions of the Democratic Party — a contention that seemed to take on added relevance after Representative Rashida Tlaib of Michigan booed Hillary Clinton from the stage of Sanders’s Friday night rally in Clive.

Clinton narrowly beat Sanders in the 2016 Iowa caucuses before the two fought a long battle that some Democrats believe ultimately weakened her going into the the general election against Trump. Sanders supporters have protested her recent claim that “nobody’’ likes him.

“I understand that, during primaries, people can get heated,’’ Warren said, “but what’s important is we come together as a party.’’

Buttigieg also hammered home a message of unity, telling voters he is the candidate who can bring together progressives, moderates, and even Republicans who are tired of Trump.

“Sometimes we get the message that we have to choose between a revolution and the status quo. I think there is another way,’’ he told the crowd.

Buttigieg sought to reassure voters worried that his low support among Black voters could doom his nationwide ambitions by having two Black mayors who have endorsed him introduce him onstage.

“When we think about Mayor Pete, and we’re talking about electability this is a mayor who can relate to everybody," said Bruce Teague, the newly elected mayor of Iowa City, who is also gay.

But Buttigieg was not able to quiet nagging concerns, even from some of his loyal fans.

Chrissy Swartzendruber, 51, of North Liberty, said she has supported Buttigieg for months because “he’s just everything that [Trump] is not.’’ But she worries about his lack of support from Black voters in South Carolina, which holds a crucial primary this month, and about his age. “I worry about a lot of things for Pete,’’ she said.

Biden leaned into his own upbeat closing argument, pitching himself as the only candidate who could heal a divided nation and restore its moral fabric.

“America’s character is on the ballot,’’ he said in a rambling speech that became more direct as he blasted Trump for maligning immigrants and other offenses.

As Sanders took the stage on Saturday night, he warned his supporters to show up in droves to prepare for the fight ahead — a battle not just with Republicans, but possibly with Democrats, too.

“This is the political reality of the moment: We are taking on the entire political establishment — both the Republican establishment and the Democratic establishment,’’ he said.

Iowa voters can be a late-deciding bunch, and some of them left the candidates’ final events still weighing their options. That included Kevin Cavallin, 48, who said he had seen 100 campaign events over the past year, but was still undecided between Warren and Klobuchar. He turned the question over in his mind as he left Warren’s event in Indianola.

“Do I want to go with someone who can beat Trump?’’ he asked, “or someone who can move the country in the right direction?’’

Globe reporters Liz Goodwin, Laura Krantz, and Jazmine Ulloa contributed to this report.