Hillary Clinton's popularity has slumped in California under an unrelenting challenge from Bernie Sanders, who has succeeded in breaching the demographic wall Clinton had counted on to protect her in the state's presidential primary, a new USC Dornsife/Los Angeles Times poll has found.
As he has done across the country this primary season, Sanders commands the support of younger voters by huge margins in advance of Tuesday's primary — even among Latinos and Asians, voter groups that Clinton easily won when she ran eight years ago. Many of his backers come from a large pool of voters who have registered for the first time in the weeks before the election.
Yet, Tuesday's outcome remains difficult to predict, precisely because of the untested nature of Sanders' following. That portends an intense fight in the final days of the campaign.
The Vermont senator has battled Clinton to a draw among all voters eligible for the Democratic primary, with 44% siding with him to 43% for Clinton. That represented a nine-point swing from a USC/Los Angeles Times poll in March, in which Clinton led handily.
But among those most likely to vote, based on their voting history and stated intentions this time around, Clinton led, 49%-39%, in the new poll. Her standing is bolstered by the reliability of her older supporters, who have a proven record of casting ballots.
She also leads convincingly among registered Democrats; 53% of likely Democratic voters supported her, to 37% for Sanders. Throughout the year, she has carried party members in every state but Sanders' home state of Vermont and next-door New Hampshire, where he won in a landslide.
As he has elsewhere, Sanders benefits here from party rules that allow registered nonpartisan voters — known in California as "no party preference" voters — to take part in the Democratic primary. Among nonpartisans who were likely to vote, he led by 48%-35%.
Sanders' chances of victory rest on big turnout of voters who typically don't vote in primaries and who — in the case of the nonpartisans — will have to navigate complicated voter rules to request a Democratic ballot.
"His base of support is young voters, low-propensity voters and [nonpartisan] voters. Not only does he have to turn them out by election day, but he has to educate all those nonpartisan voters" to request a Democratic ballot, said Dan Schnur, the poll director who heads USC's Jesse M. Unruh Institute of Politics.
"That's not to say he can't pull it off, but this may be the biggest voter mobilization challenge California has seen in many, many years."
For all the threat the primary represents, Clinton, who likely will clinch the Democratic nomination even before Californians' votes are counted, retains most of her strength in a general election contest against presumptive Republican nominee Donald Trump.
Trump has contended in recent days that he could make a run at California in November, but the poll showed that to be implausible, at best.
Fewer than three in 10 likely November voters in California had a favorable impression of Trump, and Clinton led him in a hypothetical matchup by 26 points, a margin that would represent the biggest victory in recent California history, larger even than Barack Obama's historic 24-point win in November of 2008.
Clinton's advantage would be even more dominant were she receiving the support of more of Sanders' loyalists. Among those siding with the senator in the primary, 65% said they were certain to support Clinton in the fall. Of the remainder, 10% said they would vote for Trump and 13% said they would not vote in the general election.
Eight years ago, the share of Clinton's backers who said they would not vote for then-Sen. Obama as the nominee was larger than that. In the end, the vast majority did back the party nominee.
Unifying the party has been troublesome for Democrats, who have watched their race persist as Trump consolidates backing among Republicans. Here, as nationally, unity is to some extent a one-way street.
Almost half of Clinton's supporters said they would enthusiastically support Sanders if he was the party nominee. Just under a quarter of Sanders' supporters said the same thing about Clinton.
Victoria Votino, a 21-year-old UC Santa Cruz student, will probably cast her first presidential vote for Sanders, "with reservations." She said she sees Clinton as potentially able "to get more done" as president, but Sanders' efforts to eliminate income inequality strike a chord.
"He seems more connected to the people and more a voice for the people," said Votino, who said she would be in Clinton's camp in the fall if she cinches the nomination.
Lisa von Schlegell, a 60-year-old software writer and consultant from Mendocino County, is siding with Clinton. That's despite being a socialist like Sanders, she said with a wry laugh.
"It's neck and neck and my feeling is that it's important to support Clinton," she said, adding that she was "disillusioned" at the unruly behavior of some Sanders supporters at a recent Nevada state party convention.
"She's had a long political career, some of which I disagree with. But I feel like she has worked very hard, is very competent and her intent is good."
Clinton's general election strategy is built on the notion that voter groups that gravitate to Democrats and have been maligned by Trump — including women, Latinos, Muslims and others — will band together to deny him the presidency. Trump's targets have included much of the Democratic base that helped propel Obama's two national victories.
But in the primary, her appeals to Obama's younger and more diverse voters have been successfully blunted by Sanders, whose iconoclastic and occasionally defiant campaign has captivated many of them.
The generational divide among Californians is the most obvious sign of Sanders' success, and a logical one given the contours of the campaign. With a strongly anti-establishment pitch, he has promoted a "political revolution," while she has taken on a more nuanced and incremental approach that dovetails with the comfort zone of older voters.
Among those under 50, Sanders held a 27-point advantage among all Democratic primary voters and a 21-point edge among likely voters. Among those over 50, Clinton led by 32 points among both groups.
Clinton would have more easily defied Sanders' onslaught if his inroads among the young had been limited to white voters, as happened in some of the states that voted earlier in the process. But he has expanded his reach in California; his diverse crowds here were reflected in the poll.
Among Latino voters under age 50, Sanders led, 58%-31%, not much different from his 62%-27% lead among younger white voters. The views of other ethnic and racial groups were too small to break out separately by age, but when all younger minority voters were considered, Sanders led, 59%-32%.
On the other side of the age divide, Clinton's lead was no less impressive. She led by 56%-32% among white voters over 50, 69%-16% among older Latinos and 64%-20% among older minority voters.
The same generational splits were visible when it came to gender: Clinton led by 33 points among women over 50 and by 31 points among older men. But Sanders led by 31 points among younger men and 25 points among younger women.
Clinton's campaign has been careful not to over-emphasize the historic nature of her candidacy, but she is reaping some benefit nonetheless. Among likely Democratic primary voters, two-thirds of men had a favorable view of her, while 76% of women shared that view. (Three-quarters of both men and women had a favorable impression of Sanders.)
Among those likely voters not supporting Clinton, the reasons differed by gender. Women were more likely to say she was not "genuine," while men most often cited "scandal."
As for Sanders, among the biggest reasons voters had for opposing him was their judgment that his positions are unrealistic, cited by 35% of likely voters. A significant chunk of voters also felt his background as an independent and a socialist had made him the wrong pick.
FOR THE RECORD
June 3, 1:43 p.m.: An earlier version of this article stated the wrong number for the percentage of likely Democratic voters in the California primary who told the USC Dornsife/Los Angeles Times poll that they opposed Sen. Bernie Sanders' presidential candidacy because they believe his proposals were unrealistic. The correct share is 35%, not 27%.
But he has built strength in large part because of his backers' passion. Sanders' overall favorability rating was 57% positive and 33% negative; Clinton's by contrast was 47% positive and 50% negative.
Among voters under age 30, 82% had a positive view of Sanders.
By contrast, among all California voters, only a quarter had a favorable view of Trump, and it was highly partisan: More than half of Republicans had a positive view of him, a view shared by only 21% of nonpartisan voters and a bare 7% of Democrats.
Not surprisingly, one of the groups most negative toward Trump were Latinos, only 11% of whom had a good impression of him.
Disdain for Trump helped vault Clinton into her giant lead in the general election matchup, unifying behind her Latinos, other minority groups, Democrats, nonpartisan voters, and others. Voters under 50 who deserted Clinton for Sanders in the primary said they would back her against Trump, 60%-22%.
In the Central Valley, one of the most conservative areas of the state, Clinton defeats Trump by 50%-41%. Only in the less-populated area north of Sacramento did Trump carry more support.
Among all voters, Clinton was judged more able to take on every issue voters were asked about, from the fight against terrorism, to the economy and jobs, to easing gridlock in Washington.
Trump also suffered for perceptions of his personal qualities. Almost four in 10 Republicans and nonpartisan voters said that he did not have the temperament to serve as president. Three in 10 cited his insults to women, Muslims and immigrants.
Most striking perhaps, was his potential to depress Republican turnout. Asked what they would do if Trump was the nominee, 28% of Republicans and nonpartisans said they would enthusiastically support him. Almost as many, 23%, said they would reluctantly support him. And a plurality, 43%, said they would refuse to vote for him.
The poll for the USC Dornsife College of Letters, Arts and Sciences and the Los Angeles Times questioned 1,500 registered California voters from May 19 to 31, including 412 deemed likely to vote in Tuesday's Democratic primary. The margin of sampling error is 2.9 points in either direction for all voters, 3.7 points for Democratic primary voters and 5 points for likely Democratic primary voters.
The survey was conducted jointly by the Democratic firm Greenberg Quinlan Rosner Research and the Republican firm American Viewpoint.