California nurse Katy Roemer remembers how at the height of the Ebola crisis last year, U.S. Senator Bernie Sanders marched arm-in-arm with union workers as they fought for hazmat suits and other protections to treat patients with infectious diseases.
Roemer's gratitude is why she keeps a large stash of "Bernie" stickers and posters in her car and is urging people she knows to back his White House bid. She jokes that she will be telling friends and family members: "You're not coming to dinner if you didn’t vote."
If Hillary Clinton wins the Democratic nomination, Roemer said she would vote for her in the November 2016 general election but she will not volunteer for her campaign.
Roemer's comments crystallize a risk Clinton faces as she courts organized labor -- a potential enthusiasm gap. Clinton, the Democratic front-runner, has racked up a string of formal endorsements, but many rank-and-file union members remain drawn to Sanders.
In the race for union endorsements, Clinton has more than a dozen from national unions, representing more than 10 million members. By contrast, Sanders has notched two national endorsements, for about 385,000 members.
But in many cases, there have been divisions within unions. Dozens of interviews with rank-and-file members show Sanders generating more passionate support based on his years of walking picket lines, attending social gatherings and intervening in labor disputes.
Even so, Clinton may have little trouble securing the Democratic nomination. Her commanding lead over Sanders has widened in recent weeks, but the passion gap indicates Clinton has more work to do in wooing union workers.
While the U.S. labor movement has shrunk in recent years, unions still represent millions of people, a potentially large source of votes. And union activists are often crucial foot soldiers for Democratic candidates, willing to put in long hours to knock on doors and help register people to vote.
Repaying Sanders for his support
In one indication of how far supporters are willing to go, Linda Horan, a retired member of the International Brotherhood of Electrical Workers, is calling fellow union members to urge them to back Sanders, even though Horan has advanced lung cancer that makes it hard for her to talk.
"I'm doing as much as I can," said Horan, whose cancer has metastasized to her brain. She said she wants to repay Sanders for joining a picket in New Hampshire last winter during a strike against the communications company FairPoint and for inviting the workers to dinner afterward.
The IBEW has held off from endorsing a presidential candidate, in part because of a letter-writing campaign from union members who wanted to buy more time for Sanders to woo members and build momentum.
In some cases, endorsements of Clinton by national unions such as the American Federation of Teachers and the machinists' union have generated debates among members on social media.
The Service Employees International Union, representing 2 million workers including nurses, janitors and other service workers, is one example of divided loyalties. Despite the national endorsement of Clinton, some of SEIU's local units have endorsed Sanders, as have the American Postal Workers Union and Roemer's union, the National Nurses United.
The Clinton campaign points to her efforts on behalf of workers over the years. Jesse Ferguson, a campaign spokesman, said Clinton has a "decades-long record of standing up and fighting alongside" workers.
Clinton has longstanding ties to many labor leaders, such as AFT's Randi Weingarten and Tom Buffenbarger of the machinists.
And many labor leaders view Clinton as more electable in a general election than Sanders. When the SEIU endorsed Clinton recently, the union's president, Mary Kay Henry, cited the chance of winning a general election as one reason.
General election fight looms
But even with growing expectations that Clinton will be the Democratic nominee, she is expected to need the help of union members in the general election campaign.
Steve Schale, a Democratic strategist, sees a real fight brewing for the general election and said unions will be valuable players.
"I think the GOP will get it together and nominate a sane person, and the general will be tough," Schale said. "We are going to need everyone pulling in the same direction next fall."
Schale, who said that for both parties more volunteers translates into more new registered voters and greater activism, is optimistic that union activists "will come home" and rally around Clinton once she gets the nomination.
For now, however, the split among unions continues to play out. Two days after the national union's endorsement, SEIU local 1984 in New Hampshire endorsed Sanders.
At Dartmouth College in New Hampshire, Susan Russell, secretary-treasurer of SEIU 560, had considered sitting out the Democratic primary – until Sanders announced his bid. Now Russell, who lives in neighboring Vermont, says she has already persuaded several people to back the self-described Democratic socialist.
Sitting in the union’s basement office in Dartmouth Hall, Russell wore a purple union T-shirt and hat, with a Bernie 2016 pin on the cap.
A few years ago, Sanders joined Russell and other local 560 members at a rally when the college proposed laying off union members. Dartmouth ultimately changed course.
In Oregon, nine members of local 503 emailed the international union’s executive board this month, asking them not to endorse yet, in what one union activist characterized as a “hail Mary pass” to stop a potential Clinton endorsement.
If Clinton becomes the nominee, they wrote, “she does not need our money. Let’s use our financial resources down ticket to elect economic and social justice pro-labor candidates, whether Democrat or not.”
Ed Montgomery, former deputy secretary of labor under Bill Clinton, said Clinton needs to win over organized labor. “She needs them to come to her side, and enthusiastically,” he said.
Still, Anna Greenberg, a Democratic strategist, said the highest priority for unions is electing a Democratic president, given how much is at stake on labor's agenda.
“People in the labor movement are highly motivated around winning this presidential election,” she said.
(Reporting by Luciana Lopez; Editing by Caren Bohan and Leslie Adler)