Inside Bernie Sanders' impressive showing in Iowa is a small but significant weak spot that could hinder his momentum against Hillary Clinton when the campaign moves beyond New Hampshire.
Voters of colour made up 9 per cent of the Democratic Iowa caucus-goers according to entrance poll results, and they went for Clinton over Sanders by 58 per cent to 34 per cent.
The results suggest that the senator from Vermont is still struggling to connect with Latino, African-American and other non-white voters, a deficit that will loom larger as the nominating contest expands to states with more diverse populations.
Sanders, a Democratic socialist without the youth or biracial appeal of President Barack Obama, rode a wave of young voter turnout after his campaign worked hard to organise voters on college campuses in Iowa.
David Axelrod, a former adviser to Obama who directs the Institute of Politics at the University of Chicago, said a near tie "when you're duelling with the champion is a win, even though the terrain was more hospitable to Sanders, and the diverse states beyond New Hampshire will be far more challenging for him," Axelrod said.
"He will raise big money off of [Tuesday's] showing, which could, at a minimum, prolong the race."
Clinton's advantage in Tuesday's caucus does not appear rooted in broad antipathy towards Sanders among non-white Democrats, as over seven in 10 of those in Iowa said each candidate shares their values. But healthcare stood out as one issue where Clinton has an advantage over Sanders among Democrats of colour. By 35 per cent to 20 per cent, more said they only trust Clinton to handle healthcare; 4 in 10 said they trust both candidates. White voters were evenly split, 25 per cent apiece.
A national Washington Post-ABC News poll late last month found Clinton holding a roughly 40-point lead among non-white Democratic-leaning voters. While most of these voters said they felt comfortable about either Sanders or Clinton serving as president, more than twice as many said they felt "very comfortable" about Clinton than Sanders (47 per cent to 19 per cent).
In less than four weeks, Sanders and Clinton will face off in the South Carolina primary, where black voters make up more than half the Democratic electorate. An NBC News/Wall Street Journal/Marist poll released last week showed Clinton with the support of 74 per cent of the black voters to Sanders's 17 per cent. Overall, Clinton got 64 per cent support among likely Democratic voters to 27 per cent for Sanders.
Sanders has acknowledged his need to do better at connecting with African-American and Latino voters. Sanders has spent his three-decade political career representing a state that is 95 per cent white.
Lee Miringoff, director of the Marist College Institute for Public Opinion, said good performances by Sanders in the first two states will cause "people in the around the country to take a look at him with a fresh lens. That's why South Carolina becomes very important for her to reverse the trends in states where there are fewer people of colour. She can't wait to get to South Carolina."
Bernie Sanders' strong showing in Iowa almost certainly denies Hillary Clinton a glide path to the nomination.
It's also sure to resurrect the questions about why she can't close the deal, why many voters remain cool to her and whether she truly is capable of knocking out a Republican in November.
Clinton's campaign was designed to withstand a bad night in Iowa, and a loss in next week's New Hampshire primary, where Sanders leads in the polls. She has the money, the state-by-state organisations and a spate of contests coming up that still give her the inside track.
"I think it's important to take the long view," said Mitch Stewart, a Democratic strategist and Clinton supporter.
Clinton's pitch in Iowa went like this: Sanders may talk a good game about levelling the playing field, but I can get things done. It fits her persona in voters' minds as a do-er, even a grinder - not flashy but with a determination that doesn't always come across as warmth.
• +79 Has right experience
• +60 Can win in November
• +43 Age 65 and over
• +42 Continue Obama's policies
• +37 Top issue terrorism
• +73 Honest and trustworthy
• +70 Age 17-29
• +55 Change to more liberal policies
• +52 Cares about people like me
• +43 Independent/other.