After hearing four Democratic presidential contenders speak in Des Moines, she still cannot decide who to support when Iowa kicks off the 2020 election with its Democratic caucuses on Monday.

As temperatures hovered around -15C in the state capital, she listened as Elizabeth Warren, Joe Biden, Pete Buttigieg and Amy Klobuchar made their case to the Iowa State Education Association, part of their frantic last-minute campaigning in the Midwestern state that decides who emerges with the early momentum.

“I support all of them. I love them so much,” says Ms Rosheim, 70, who is volunteering for Ms Warren but has not committed to supporting her in the caucuses. “I really like her plans, but I also like Amy a lot. And then people tell me, ‘We gotta like Biden because he’s got name recognition and he’ll win’ . . . It’s so hard to decide.”

Ms Rosheim is not alone. Iowans are famous for not making up their minds until the last minute. A Des Moines Register/CNN poll in early January showed that only 40 per cent had picked their first choice.

As the Democrats prepare for a five-month marathon primary process to decide their candidate, the party is more united than ever on the need to beat Donald Trump. After winning the 2018 midterms by a margin of 9 percentage points, and with Mr Trump’s poll rating still historically low for a president starting his re-election campaign, many in the party hope they can harness that anti-Trump feeling to beat him despite the strong state of the economy.

But they are fiercely divided about what sort of Democrat is best-suited to take on the president, whether it is a progressive politician who can motivate the party’s base of minorities, younger voters and women, or whether they should choose a more moderate figure who can appeal to working-class whites and suburban Republicans turned off by the president’s bluster.

Audrey Baatz embodies the high level of uncertainty. Speaking at a Buttigieg rally in Emmetsburg, north-west Iowa, the independent-leaning woman is mulling over the moderates — Mr Buttigieg, the former mayor of South Bend in Indiana, Mr Biden and Ms Klobuchar, senator from Minnesota. But she thinks any of the leading contenders could emerge as the winner on Monday.

“The people of Iowa are just so undecided, especially in rural areas,” Ms Baatz says. “Any four or five people could win Iowa. It’s that close.”

Heidi Heitkamp, a former North Dakota Democratic senator, says voters are struggling because of the crowded field, which still boasts 11 candidates even after 16 have dropped out.

“You go to a Mayor Pete event and you go, ‘Wow I was blown away’, and then you go to Amy’s event and say, ‘Oh man she makes a lot of sense’. There’s so many people . . . active in Iowa that it makes the choice harder.”

But a majority of Iowans agree on one thing. J Ann Selzer, the Des Moines Register/CNN pollster, says 58 per cent think it is “extremely important” to pick someone who can beat Mr Trump, which Ms Heitkamp says is common. “If you ask any Democratic voter in North Dakota, their main goal would be to defeat Donald Trump.”

Judy Lentz, a Democrat at the Emmetsburg event, says she likes Mr Buttigieg but worries about his electability. “It is going to come around to who we think can beat Mr Trump,” she says. At a separate event nearby in Arnolds Park, Carolyn Brown, who is leaning towards Mr Biden, agrees that the only question is: “Who can beat Trump?”

Strengths Strong name recognition, popular among African Americans, very experienced
Weaknesses Has stumbled in debates, too establishment for some young voters
Bernie Sanders, senator from Vermont

Strengths Loyal support among young voters, who consider him authentic and bold
Weaknesses Distrusted by the party elite, too extreme for some Democrats
Elizabeth Warren, senator from Massachusetts

Strengths Also strong, popular with young voters and many women who want to see a female president
Weaknesses Lost momentum after heavy criticism of her healthcare plan

Strengths The fresh face in the race, has been able to straddle moderate and progressive camps
Weaknesses Inexperience. Some more conservative Democrats may recoil at his sexuality.

Iowa is notorious for surprises. Jimmy Carter, then a little-known southern governor, came from nowhere to win the state on his way to the presidency in 1976. In 2008, Barack Obama came from far behind to beat Hillary Clinton, a result that showed he could win white voters in a rural state. Howard Dean was the frontrunner in 2004 until John Kerry sprinted ahead in the last week, knocking the former Vermont governor into third place. And four years ago, Mr Sanders stunned Mrs Clinton again by coming tantalisingly close to winning.

“Nobody has any idea,” Mr Dean stresses. “I had no idea what was going to happen when I was there.”

On the question of how each contender would fare against Mr Trump, polls show Mr Biden winning by 4 points, ahead of Mr Sanders, Ms Warren and Michael Bloomberg. Mr Buttigieg is the only top Democrat who would lose. But when it comes to Iowa Democrats, polls show they remain at odds over who should be the standard bearer.

After long being the frontrunner in Iowa and New Hampshire, which holds the first primary a week later, Mr Biden was overtaken in Iowa last summer by Ms Warren. The Massachusetts senator was then eclipsed by Mr Buttigieg, who in turn was passed by Mr Sanders, before Mr Biden returned to the top of the group. Yet in the last week, Mr Sanders has moved ahead, while Ms Klobuchar has entered double-digits for the first time in the 2020 race.

Mr Bloomberg does not register in Iowa because of his decision not to campaign in the state. But he has jumped into fourth place in national polls, propelled by tens of millions of dollars in television ads that he hopes will catapult him into contention when more than a dozen states vote on the delegate-rich Super Tuesday on March 3, when 13 states will vote.

The critical distinction is whether the candidates fall into one of two camps — moderate or progressive.

Mr Biden and Ms Klobuchar say the way to beat Mr Trump is to attack from the middle, appealing to Democrats and independents who backed him in 2016 by staking out moderate positions. But the progressives, Ms Warren and Mr Sanders, urge bold ideas, such as a fully nationalised healthcare system. They argue that a lack of radicalism helped create the conditions for Mr Trump to win since they did too little to help struggling Americans.

Speaking in Des Moines before returning to Washington for Mr Trump’s impeachment trial, Ms Warren took aim at the moderates, saying, “Some folks in our party don’t want to admit” that the US is in a “crisis” over everything from the gap between the rich and poor, the soaring cost of healthcare and high levels of student debt.
A graphic with no description

“If they think that nibbling around the edges of big problems, running some vague campaign is somehow the safe strategy, they’re wrong,” Ms Warren told a packed gymnasium at Weeks Middle School. “If all the best Democrats can offer is business as usual after Donald Trump, Democrats will lose. We win with big ideas.”

While Mr Biden has generally steered clear of attacking his rivals by name, he aired an ad saying it was “no time to take a risk” on other candidates.

Mr Dean says there are plausible arguments on both sides. “Biden is saying I’m better because I can appeal across a broader spectrum. Bernie is saying you can’t win unless you motivate the hell out of people, and Elizabeth is saying the same,” he says. “The number one criteria is who can beat Trump and nobody knows.”

Each candidate has strengths. Mr Biden resonates with white working-class Democrats who backed Mr Trump and African-Americans who remember his time as vice-president to the first black president. Mr Buttigieg, a gay, former mayor and army veteran, is the fresh face, while the folksy Ms Klobuchar touts her results-driven approach in Congress.

Ms Warren and Mr Sanders have strong appeal among younger voters, while the Massachusetts senator is also making a big pitch to women — in a push that helped her win some converts at her Des Moines event. “I came here to Iowa to support Pete Buttigieg, but I came to this town hall and she just spoke to me,” says Hailey McGuire, a high-school student. “She just radiated girl power.”

Yet all the contenders also have significant challenges. With the exception of Mr Biden, most lag far behind with black voters, which raises questions about their ability to connect with a key segment of the Democratic electorate. Mr Biden has struggled at times with fundraising, which could be a problem as expensive TV ads become important in the bigger states. He also fares less well with younger voters than the progressives.

Speaking after a Biden rally at Simpson College, Kathryn Hays, a politics student who plans to support Ms Warren in the caucus, says her generation is gravitating to Mr Sanders and Ms Warren because of their idealism. She says Mr Sanders has been “radical throughout his whole political history”, which her friend Samantha Wuebker explains is “probably why Elizabeth is also doing so well among our generation too”.

Mr Buttigieg is also competing for the same college-educated voters as Ms Warren, but has to overcome concerns about his inexperience. At one event, he also faced a common question about his “really low” support among black voters. “African American voters who know me best support me,” he said.

Ms Warren also needs to boost her support among black voters, while she and Mr Sanders must show that they can win over enough moderate Democrats to beat Mr Trump in November. Illustrating that concern, Robert Brammer, a 70-year-old who was attending a Klobuchar event in Des Moines, says he prefers Mr Sanders’ progressive ideas but will campaign for the Minnesota senator because she is more pragmatic.

As the race moves out of the predominantly white Iowa and New Hampshire into the more diverse states, an important question is who can recreate the “Obama coalition” — a grouping of white voters in the north, black voters in the south, Hispanics, millennials and women — that swept Mr Obama to the White House in 2008.

“What it is going to take to beat Trump is to get out our voters,” says Mr Dean. “Our voters are under 35, female and people of colour. All of those three groups have to be enthralled to a degree with a candidate. The problem is the Democratic candidates all speak to different people, and that is why nobody can decide.”

Kaleb Autman, a 17-year-old high-school student who came to Iowa with Mikva Challenge, a group that helps young people to become engaged in politics, will vote for the first time this year. But he worries that some of the Democrats are too focused on winning over Trump voters and not enough on expanding the party.

“They focus too much on how to get Trump’s people on our wagon . . . rather than focusing on the people who didn’t show up to vote,” he says. “If you want to win this election, you have to go for new voters.”

One of the unusual factors is that three of the top candidates — Mr Sanders, Ms Klobuchar and Ms Warren — have had to stay in Washington for much of the past two weeks because of the impeachment trial, giving an advantage to Mr Biden and Mr Buttigieg. Yet the restraints could help Ms Warren receive a boost over her fellow senators since she has one of the best on-the-ground organisations.

Iowa often has a winnowing effect on the race but the big field — the number of undecided voters, the trial-related restraints on the senators and the fact that the candidate with the most cash, Mr Bloomberg, is ignoring Iowa — means the caucuses may be even more unpredictable than ever.

“The old saying is there are three tickets out of Iowa [for the leading candidates],” says Mr Dean. “Clearly that is not true this year.”