OSAGE, Iowa (AP) -- As Joe Biden wrapped a bus tour of Iowa this week, the elderly crowd gathered at VFW Hall 7920 was a stark reminder of the former vice president's struggle to attract young people.
Bernie Sanders, meanwhile, needs to strengthen his standing with older voters. Elizabeth Warren has room to grow among those without college degrees. Pete Buttigieg's support with African Americans is negligible, and the buzz that surrounds Amy Klobuchar belies the fact that she's barely registering with virtually any key demographic.
Just over a week before the Iowa caucuses jump-start the Democratic contest, polling and interviews with campaign officials suggest each of the leading candidates has glaring holes in his or her political bases. The gaps raise serious questions about their ability to build a broad coalition like the one Barack Obama twice used to win the presidency — questions that strike at the heart of electability as Iowa Democrats seek, above all, a nominee who can rally the nation to defeat President Donald Trump in November.
"They need to generate enthusiasm," 69-year-old retired attorney Tom Delgado said of the Democratic field while waiting for Biden to arrive at the VFW hall in Osage, Iowa. "I don't think any one person in the race right now can do it."
Delgado's concerns echo those of Obama veterans like David Binder, a pollster who was involved with both presidential victories and now worries that no one in his party's 2020 class is a lock to reassemble the vaunted "Obama coalition" of three core groups: young people, minorities and working-class whites.
"Every Democrat needs to work as hard as they can to coalesce those groups," Binder said. "I think some have shown in the polling that they can have a base with one or two of them, but not the whole coalition."
He added: "If any one of those elements falls off, then it's going to be very difficult for a Democrat to win."
The challenges for each of the candidates — and the party as a whole — have triggered a sense of alarm from campaign operatives and Democratic officials, several with ties to Obama, who worry that mathematical realities shaping the electorate could make it difficult for any of the candidates to defeat Trump without significant improvement over the coming months.
The Republican president cobbled together a winning coalition of his own in 2016 by drawing heavily on white, non-college-educated voters, and his campaign sees opportunities to expand his support with Latinos, among other key demographics. At the same time, Trump is trying to stoke Democratic divisions, betting that rifts between core Democratic constituencies will help him win a second term.
Democrats hope that shifts in the electorate, particularly among educated voters and women, could broaden the path to the presidency for the Democratic nominee. But there is a broad acknowledgement that few groups of Democratic voters are passionate about their choices in 2020.
"I'm deeply concerned about our chances this fall," said Bill Burton, an Obama aide who pointed to Obama's strength with a diverse set of voters, particularly working-class whites in more than 200 counties across the nation that backed Trump in 2016. "It's going to take a candidate who can stitch together the broadest possible coalition to beat Donald Trump."
The candidates are aware of their deficiencies, but there are no easy answers.
Buttigieg, whose struggles with African-American voters have haunted his campaign for months, said in an interview that, "No one is hurting more under the divisiveness and mismanagement more under the Trump administration than communities of color."
"I think now is our chance, with one consistent message, to build perhaps the broadest range of Democratic voters that we've had in some time," Buttigieg added. "I think it'll take patient, coalition-building."
Biden senior strategist Anita Dunn acknowledged a weakness with younger voters when pressed, but she suggested that Biden's competitors have much more to worry about with other demographics.
"Other campaigns may want to think about how they can engage better with older voters, who actually vote at a greater propensity than younger voters do," Dunn said. "But clearly, if you look at where this race is right now and the kind of support each candidate has, Biden, by far, has the best base to expand."
Sanders' chief strategist, Jeff Weaver, highlighted Sanders' strong standing with young minority voters in particular, a group that was not largely engaged in 2016. To showcase that strength, the campaign is hosting multiple events in Iowa this weekend with New York Rep. Alexandria Ocasio-Cortez, a 30-year-old liberal superstar who will stand in for Sanders as he participates in Trump's impeachment trial.
Sanders has also aggressively courted labor unions, whose working-class voters form an important part of his political base, Weaver said.
"The key to victory is putting together a coalition that includes people of all races, excites and energizes young people, and brings working people back into the Democratic Party," Weaver said. "Bernie can bring together the various pieces."
Campaigns and independent operatives believe a winning coalition in 2020 will bear some differences from Obama's coalition more than a decade ago. Democratic strategists are looking particularly at women and college-educated voters across America's suburbs, who have shifted away from Trump's GOP in a series of elections since he took office.
"We're looking at a new electorate now," said Katie Drapcho, director of research and polling for the pro-Democrat super PAC Priorities USA.
Specifically, she said the Democratic Party and its nominee will have opportunities to win drawing largely from three key groups: non-college-educated women, suburban voters who backed Republican Mitt Romney in 2012 but sided with Democrat Hillary Clinton in 2016, and working-class voters who twice backed Obama yet swung to Trump in 2016.
Still, Democrats cannot afford significant slippage among the core pieces of the Obama coalition. And leaders from those factions are concerned.
Civil rights activist Al Sharpton said he's deeply "disturbed" that the two highest-profile African American candidates running for president, Kamala Harris and Cory Booker, have already been forced out of the race. He said "it's too early to tell" whether any of the remaining Democrats can energize the black vote to a level close to Obama, the nation's first black president.
"I do not see one singularly able to do it yet," Sharpton said.
Like other Democratic leaders, he's hoping that Trump himself will ultimately persuade black voters to turn out en masse even if the ultimate Democratic nominee does not excite them.
"The biggest organizer and energizer of black voters is Donald Trump," Sharpton declared.
It's much the same with another pillar of the Obama coalition, young voters, who have been more engaged in the Trump era but have shown little excitement for most of the current Democratic candidates. Sanders, the self-described democratic socialist who has called for a political revolution, is the big exception.
Calvin Wilborn, the former president of the College Democrats of America, said it's unfair to compare any 2020 Democrat to Obama.
"Obama spoiled us. Not only did he move legislation and most of his ideology aligned with us, but he was charismatic," Wilborn said. "When you set the bar so high, it's hard for others. We're waiting for the same level of inspiration."