DES MOINES — With the Iowa caucuses a week away and senators briefly sprung from their impeachment-induced confinement on Capitol Hill, the Democratic presidential candidates and their surrogates spilled out across Iowa on Sunday.
They gave their stump speeches. They took photos and shook hands. They tried mightily to address the elephant in the room — a series of polls showing Senator Bernie Sanders of Vermont pulling even with or ahead of the longtime front-runner, former Vice President Joseph R. Biden Jr. — without appearing to concern themselves with it.
Former Mayor Pete Buttigieg of South Bend, Ind., carried on the long tradition of campaign-trail subtweeting, attacking Mr. Sanders and Mr. Biden unmistakably but without naming them.
“The country will be crying out for a president capable of unifying and healing the American people,” Mr. Buttigieg said at a rally in West Des Moines, a clear shot at Mr. Sanders.
Later, at a town hall televised on Fox News, he said that he had “heard some folks saying” that now was not the time for voters to take a risk — Team Biden is running an ad arguing exactly that — but that the real risk “would be to try to go up against this president with the same old playbook that we’ve been relying on.”
Senator Amy Klobuchar of Minnesota, who has gained ground in recent weeks but is still polling a distant fifth here, tried to focus on crowd sizes instead — and on somewhat better poll results she received in New Hampshire, which will vote the week after Iowa.
“We are seeing this overwhelming number of people showing up on a Sunday afternoon,” Ms. Klobuchar told reporters in Ames. “We’re seeing the poll that we just saw this morning in New Hampshire, in double digits, just a few points away from many of my maybe more well-known competitors on the national stage.”
And besides, how much attention should voters pay to polls to begin with? “Let’s see what happens when people are actually showing up,” she said.
As always, the undertone — and sometimes the overtone — was each candidate’s so-called electability against President Trump. From Davenport in the east to Sioux City in the west, the candidates circled one another, jostling to cast themselves as the most viable contender for November.
“Can we just address it right here? Women win,” Senator Elizabeth Warren of Massachusetts said at an event in Davenport, invoking the same argument she made at this month’s debate when she noted that she and Ms. Klobuchar were the only people onstage who had never lost an election. “Women candidates have been outperforming men candidates since Donald Trump was elected.”
Mr. Sanders and Mr. Biden, meanwhile, continued to spar with each other, each seeing the other — justifiably, based on recent polls — as his biggest threat.
After a weeklong public fight over their records on Social Security, they turned to climate. At an event in Perry on Sunday, Mr. Sanders shot back at Mr. Biden for his remark a couple days earlier that “not a single solitary scientist” considered Mr. Sanders’s climate plan workable.
“Well, Joe, you’re wrong,” Mr. Sanders said. “Many leading scientists agree with our plan, and in a few days we’re going to have a long list of scientists who agree with our plan.”
In Des Moines, Mr. Biden drew voters’ attention to what is arguably his biggest strength nationally: his strong support from black voters. It is a key part of the same electability argument that echoed across the state all weekend: Black voters are an essential constituency in the Democratic Party.
“I know a lot of folks out here were wondering, ‘Why does Biden get such overwhelming support from the African-American community?’” Mr. Biden said. “Because that’s what I’m part of. That’s where my political identity comes from. And it’s the single most loyal constituency I’ve ever had.”
As for the Iowans he and everyone else were courting, some of them ended the weekend as torn as they had begun it.
“It’s hard to tell. They are all so similar,” said Ann Clary, a state budget analyst who attended one of Mr. Buttigieg’s events on Sunday but is also considering caucusing for Mr. Biden and Ms. Klobuchar. “Sometimes I can’t fall asleep at night. I just can’t stop thinking about it.”
As night fell, Mr. Biden and Mr. Buttigieg went on with business as usual, looking forward to another full week of events. And then there were the senators.
Round and round the state they went: Ms. Warren from Davenport to Cedar Rapids, Ms. Klobuchar from Waterloo to Ames to Des Moines, Mr. Sanders from Perry to Storm Lake to Sioux City.
They had to hurry, because soon the day, and their window, would be over.
“I could have literally done these in every town and revisited all 99 counties again,” Ms. Klobuchar told reporters wistfully after an event in Ames. “That was one of my secret plans, but it’s now been dashed, since I turn into a pumpkin at midnight.”
Reporting was contributed by Nick Corasaniti from Ames, Iowa; Sydney Ember from Ames and Perry; Reid J. Epstein from West Des Moines and Storm Lake; Shane Goldmacher from Davenport; Thomas Kaplan from Des Moines; and Lisa Lerer from Perry.