NEWTON, Iowa—The speakers blared Katy Perry and Taylor Swift as the modest crowd waited for Hillary Clinton to arrive at a rally in a middle-school gymnasium here last Thursday. But a more age-appropriate choice for the mostly gray-haired audience might have been Carole King, or even Peggy Lee.

Two nights later there was probably more purple or pink than gray hair in the audience when an overflow crowd of 3,500 greeted Bernie Sanders at the University of Iowa basketball arena. The youthful throng swayed and clapped through performances by indie bands Foster the People and Vampire Weekend before enveloping the rumpled 74-year-old Sanders in roars of adulation that rolled across the arena like waves.

The generational chasm between supporters of Clinton and Sanders is just one of the ways that the unexpectedly competitive 2016 Democratic presidential race is dividing the Democratic coalition.

Some of the divisions emerging between Clinton and Sanders reprise and even intensify the contrasts that emerged between the former First Lady and then-Senator Barack Obama during their epic 2008 struggle for the nomination. But in other respects, early polling suggests that this contest is deconstructing and recombining the Obama and Clinton coalitions from the 2008 race into new alignments—creating fresh opportunities and challenges for each of the principal contenders.

In the 2008 race, Clinton and Obama both quickly developed patterns of support that persisted, with remarkable consistency, throughout their marathon competition. The demographic grooves were so consistent that Howard Wolfson, the Clinton campaign’s communications director, once observed that the competition in each new state amounted to a mathematical equation measuring Clinton’s base of working-class whites and Latinos against Obama’s foundation of upper-income whites and African Americans.

In fact, a cumulative analysis of all the 2008 Democratic exit polls conducted by the ABC pollster Gary Langer, found that Clinton enjoyed big margins among white women without a college education (66 percent); Hispanics (61 percent); seniors (59 percent); non-college-educated white men (56 percent); and college-educated white women (54 percent). Obama’s narrow victory was built on big advantages of his own among college-educated white men (55 percent) voters under 30 (58 percent) and, above all, African Americans (82 percent).  These patterns of support translated into a relatively narrow gender gap (Clinton ran nine percentage points better among women than men) and also a relatively restrained partisan gap (Obama ran seven percentage points better among self-identified independents than among Democrats).

Compared to 2008, the early 2016 polling suggests that in the Clinton-Sanders race, the generational, gender, and partisan gaps are widening, while the class contrast is diminishing, and the racial allegiances are in flux.

The cumulative effect of all this resorting leaves Clinton today with a clear edge over Sanders—even if he wins the first two states of Iowa and New Hampshire. But it also indicates Clinton’s margin for error is eroding and that Sanders could grow to genuinely threaten her if he can parlay success in the early states into a second look from key constituencies now tilting toward her—particularly Latinos and blue-collar white women. “I think we are a long way from knowing what Bernie can do with different groups of voters,” insists Tad Devine, the Sanders campaign’s senior strategist.

In Democratic polling so far, the deepest and most consistent fissure between Clinton and Sanders is age. As the contrasting events in Newton and Iowa City late last week demonstrated, this race appears poised to generate an even wider generation gap than the 2008 contest.

Sanders has proven an unlikely magnet for younger white voters: His camp flatly predicts he will win Iowa if voters under 30 match or exceed their 22 percent share of the vote here from 2008. There’s reason for that confidence. NBC/Wall Street Journal/Marist Institute polls released last week in the virtually all-white first two states on the calendar showed Sanders leading Clinton among likely voters younger than 45 by crushing margins in Iowa (70 percent to 26 percent) and New Hampshire (75 percent to 21 percent); in South Carolina, Sanders led Clinton by almost exactly two-to-one among whites younger than 50, according to figures provided by Marist. The Des Moines Register/Bloomberg Iowa poll released Saturday night gave Sanders over three-fifths of likely voters younger than 35.

Among older voters, the picture was very different: Clinton drew three-fifths of voters older than 45 in Iowa and two-thirds of whites older than 50 in South Carolina; in New Hampshire, she split older voters with Sanders. The DMR/Bloomberg survey put her at nearly two-thirds of Iowa voters 65 and older.

The contrasting priorities that separate voters along this spectrum are quickly apparent at rallies for the two candidates. Many middle-aged and older voters respond to Clinton’s argument that she can deliver more practical change than Sanders, whose sweeping proposals she derides as politically infeasible. “For me, personally, it’s experience that is drawing me to Hillary, because even though I like everything Bernie says, it’s a little too idealistic and I’m a little more real world at my age,” said Linda Erickson, a retired school counselor from Newton, as she waited for Clinton to arrive. Jennifer Kerns, a 41-year-old community college instructor, reached a similar conclusion: “My pragmatism is winning out over my idealism a little bit,” she said. “I think it’s very important we pick a candidate who can win.”

The emotional high point of Clinton’s rally in Newton came when she comforted a 73-year-old woman who broke down recounting how she had lost her house after her husband died. For a moment, Clinton seemed to be channeling her husband’s instinctive empathy as she hugged the small, white-haired woman. “We have got to do more to help people,” Clinton said quietly, her voice then rising. “Let’s move away from all this mean-spiritedness and insulting.”

At Sanders’s University of Iowa rally, his youthful supporters often expressed respect for Clinton, but repeatedly volunteered the sense that she was too tarnished by compromise and connections to bring the transformative change they believe the Vermont senator can ignite. “He doesn’t try to pretend to be something he’s not, and he’s very straightforward in what he says he’s going to do,” said Kathleen Trombly, a junior at the university. “I think she has some great ideas but I get a vibe from her that she does try to be something she’s not.”

Mary Traxler, a sophomore from Drake University, drove two hours to Iowa City to see Sanders Saturday night. “I think [Clinton] would be a fine president,” Traxler said. “But I think she has a lot of financial ties to big business and Wall Street. It made me feel kind of doubtful that she was on the side of people who can’t contribute to a super PAC.”

Especially frustrating for Clinton supporters has been Sanders’s strength among younger women like Trombly and Traxler. “I would love to see a woman president in my lifetime; that would be great,” said Hannah Palmer, a 23-year-old working in retail. “But my ideas align with Bernie’s.” Besides, Palmer said, there will be other opportunities to elect a woman president: “I don’t think it’s her or nothing at all.” Trombley took a similar view: “I’d rather vote for someone I fully believe in, rather than for someone based on gender.”

Geoff Garin, the chief strategist for Clinton’s 2008 campaign who is now polling for a Super PAC supporting her, says Clinton faced a similar youth deficit early in the 2008 race but gradually chipped away at it. “In 2008, Hillary improved with younger voters as the campaign went on, and she particularly improved with younger women,” Garin said. ”I can imagine that happening again.” Garin believes Clinton has better prospects of regaining ground among older Millennials (roughly aged 25-34) than the very youngest members of the giant generation (aged 18-24). “The older Millennials, who experienced the difficulties that Obama faced in achieving change, will be more attuned to the realism-based argument—and I could imagine that the very younger part of the age group will be less open to a case that is built around the need for realism,” he says.

Notwithstanding Sanders’s surprising strength with younger women, the early polls point toward a large overall gender gap in the 2016 race—perhaps even wider than the 2008 race produced. That may be less because Clinton’s support is rising among women overall—although that’s occurring in some polls—than because she’s lost ground since 2008 among blue-collar white men. Put another way, the gender gap may be widening because the class distinction is narrowing.

Sanders began the race as a classic “wine track” candidate relying primarily on support from younger and well-educated white liberals. But polls in Iowa and New Hampshire now clearly show him advancing from that beachhead to run competitively with working-class whites. In particular, although non-college white men gave Clinton a big advantage in 2008 over Obama—an African American with a Harvard pedigree—the latest NBC/WSJ/Marist polls show Sanders drawing a commanding three-fourths of those blue-collar white men in New Hampshire and three-fifths of them in Iowa. And just as in 2008, Clinton is struggling among college-educated white men, trailing Sanders among them in both states, according to the latest surveys.

If Sanders’s best groups in these early polls are younger voters and both upscale and downscale white men, Clinton’s strongest assets are minorities and white women with and without advanced education. Her strength with the white women largely replicates her showing from 2008. Her advantage with minorities marries her 2008 strength among Latinos with renewed appeal to African American voters, who bolted toward Obama once he demonstrated his viability by beating Clinton in Iowa.

If voters continue to divide along the lines now evident in these early polls, Clinton would win virtually every big state. Because of Clinton’s continuing appeal to white women, Sanders would not generate a large enough margin among all whites to overcome her lead among minorities in large diverse states like New York (where minorities cast just under one-third of the 2008 vote), Florida (about one-third), Virginia and New Jersey (about two-fifths), Illinois (over two-fifths) California (nearly half) and Georgia and Texas (over half). Without improving among minorities, Sanders’s strength might be limited to caucus states (which reward passion among smaller groups), and preponderantly white liberal states like those in New England, the upper Midwest (Minnesota and Wisconsin) and the West Coast (Washington and Oregon).

The members of Sanders’s camp believe they can expand beyond those limits by dislodging two bricks in Clinton’s reconfigured 2016 coalition. They are hoping to replicate their gains among working-class white men with progress among working-class white women. Perhaps most intriguingly, they say they see evidence that Clinton’s hold on Hispanic voters is looser than in 2008. “I’m not saying we’re going to win overwhelmingly with Latinos,” said Devine. “[But] she is not going to win Latinos against us the way she did with [Obama].” The Nevada caucus, which follows immediately after Iowa and New Hampshire for Democrats, will provide the first test of that theory.

Sanders faces one final hurdle that hasn’t received much attention, but could loom large as the race progresses. Even in the national and early state surveys that show the best overall results for him, he often substantially trails Clinton among self-identified Democrats. The most recent national surveys from NBC/Wall Street Journal, CNN/ORC and ABC/Washington Post all show her winning about three-fifths or more of Democrats, with Sanders running much better (and often leading) among independents. The new Marist state polls in Iowa and South Carolina find similar patterns there. Only in New Hampshire do polls find Sanders leading among Democrats.

Though independents play a large role in some states (particularly the New Hampshire primary), many states limit voting solely to registered Democrats; overall, voters who identified as Democrats cast almost exactly three-fourths of the 2008 primary ballots, according to Langer’s cumulative analysis. Like John McCain, who displayed a similar pattern of support early in his 2000 race against George W. Bush, Sanders will likely find it difficult to win a party’s nomination if he can’t convince most of the voters in that party to support him. “In terms of the nomination, Hillary’s strength among Democrats is more important than Bernie’s strength among independents in that we are going to have a lot of states where only Democrats can vote,” says Garin. Devine doesn’t entirely disagree. “We have got to win enough support from Democrats to allow the other people we bring in to get us over the top,” he says. Monday’s vote in Iowa will offer the first test of whether Sanders can scale that wall.