DES MOINES — In a packed arena here last week, President Trump focused on home-state issues, mentioning farmers 47 times, touting recent trade deals and taking credit for Iowa's low unemployment rate.

Trump won Iowa decisively in 2016, and while Democrats made gains two years later, the party’s presidential candidates — after hundreds of rallies, town halls and parties over the past year — now face a decision: whether to bother coming back.

“I worked so hard for this state. I worked so hard,” Trump said as he opened his rally. He added, “We’re going to win the great state of Iowa, and it’s going to be a historic landslide. If we don’t win, your farms are going to hell.”

Iowa has long been competitive, but Trump’s nine-point victory and the state’s demographic makeup place it at the heart of a central question facing Democrats: Can they win back rural, white and industrial voters, or is the party’s future elsewhere?

“How did Donald Trump win your state — a purple swing state — by almost 10 points?” Democratic presidential candidate Andrew Yang said at a Des Moines rally Saturday. “Why is it that this state has gone from blue or purple to red over the last number of years? That’s a fundamental question, and the Democrats have not been addressing it.”

Some Democrats insist that Trump is vulnerable in Iowa, highlighting his flagging approval numbers and the 2018 midterm elections, when Democratic candidates performed well in areas that Trump had previously won.

Former South Bend, Ind., mayor Pete Buttigieg in particular has argued that he can capital­ize on those areas. Iowa is home to more counties that flipped from Obama to Trump than any other state, and Buttigieg has boasted of touring 25 of those 31 counties.

“The president is going to be in big trouble here,” said Matt Sinovic, executive director of the liberal group Progress Iowa. “His approval numbers are down, and every other underlying factor is what points to that.”

But it’s no accident that Trump chose to hold a rally in Iowa — before a capacity crowd at Drake University’s Knapp Center — just days before the Democrats in this state began the process of choosing his opponent. Trump’s strength in rural counties propelled his victory in Iowa, which saw the largest swing away from Democrats among the six states that flipped from President Barack Obama to Trump between 2012 and 2016.

Some Democrats’ complaints about Iowa’s first-in-the-nation role reflect a broader concern that its demographic profile is out of step with an increasingly diverse Democratic Party that performs best in areas with a larger share of minority voters. More than 90 percent of the population in Iowa is white.

Jim Messina, who served as Obama’s 2012 campaign manager, said Trump and Republicans were “heavy favorites to win in the general election” in Iowa.

While Democrats’ chances in Iowa ultimately depend on which candidate they nominate, Messina said, the election is likely to be won or lost in other states. Iowa, he said, is “clearly below the mid-tier of Midwestern states of Michigan, Pennsylvania and Wisconsin.”

Iowa’s recent drift is epitomized by Sen. Joni Ernst, a conservative Republican who won her seat after the 2014 retirement Sen. Tom Harkin (D), a longtime liberal icon. Ernst caught fire that year with an ad declaring: “I grew up castrating hogs on an Iowa farm, so when I get to Washington, I’ll know how to cut pork.”

But amid a Democratic surge in 2018, Democrats retook two of Iowa’s four U.S. House seats, flipping a 3-1 Republican edge to a 3-1 Democratic advantage in the state’s U.S. House delegation. But both senators and the governor are Republican, and it’s not clear if 2018 is a blip or a long-term trend.

For now, Trump’s approval rating is underwater in Iowa, with 53 percent of voters disapproving of his performance and 44 percent approving, according to a poll released in December by Morning Consult. A January poll released by the Des Moines Register in coordination with CNN and Mediacom found that only 34 percent of Iowans said they would “definitely” vote to reelect Trump.

Democrats say issues such as Trump’s efforts to repeal the Affordable Care Act have badly damaged his standing in the state. At his rally, Trump spent little time on health care, instead arguing that he has helped drive down the state’s unemployment rate, which has been below 3 percent since October 2017, and touting his trade deals.

He also cited a New York Times-Siena College poll that showed him beating his Democratic presidential rivals, whom he characterized as radical left-wingers. “They have me pitted against every one of the socialists, and we’re winning by a lot,” Trump said, exaggerating the narrow lead he holds against most Democrats in the poll, some of which fall within the margin of error.

Trump took particular aim at Sen. Bernie Sanders (I-Vt.), who describes himself as a democratic socialist. “Under three years of my administration, net farm income has already gone up nearly 50 percent and will now be rising even faster,” Trump told the crowd. “What are you going to do? You are going to vote for Bernie? You are going to vote for Bernie?”

Still, Trump’s trade war has clearly had a residual effect on the state’s farmers. Ernst, speaking on CNN’s “State of the Union” on Sunday, said that while farmers were experiencing “hurt” during the trade war, they continue to support Trump.

“What I heard from one farmer, she said, ‘You know what? I’m tightening my belt. Things are tougher right now, but I know in the long run this is going to be better for my grandchildren,’ ” Ernst said.

And Trump’s support among the state’s Republicans has remained strong. According to a Des Moines Register-CNN-Mediacom poll released in November, 85 percent of Republicans approve of Trump’s job performance. The president’s campaign dispatched more than 80 surrogates to Iowa ahead of the caucuses as a show of force aimed at shoring up that support.

State Sen. Tom Greene (R), one of those surrogates, predicted that the president will win easily in November. Trump “carried the 93 of 99 countries in Iowa and carried the state by 190,000 votes in 2016,” he said. “I expect similar results in 2020.”

Kayleigh McEnany, a spokeswoman for Trump’s campaign, said the surrogates would be speaking at the Republican caucuses, where Trump does not face serious competition, to get ready for the effort in November.

“This is an opportunity to work out those ground-game muscles and make sure we have our ducks in a row,” she said. “We’re not ever going to take a state for granted.”

Aside from Florida and Ohio, Iowa is the only state that has flipped between parties three times since 2000. After going for Republican George W. Bush in 2004, it voted twice for Obama before turning to Trump.

In 2016, Trump visited Iowa seven times in the final three months of the election compared with three for Democrat Hillary Clinton, an investment that appeared to pay off.

Sinovic said this time would be different now that voters have seen how Trump handles bread-and-butter issues such as health care.

“Americans and Iowans are furious about them trying to take away our health care,” Sinovic said. “That has been the number one issue when it comes to these national elections these last couple years, and it’s going to continue to be.”