Sandy Reding and Kenny McCall are on a quiet subdivision next to the University of Nevada campus in Las Vegas. It’s Friday morning, a day before Nevada’s Democratic Party holds its 2016 caucus, and they are among 250 registered nurses from across the U.S. who are members of the National Nurses United union who volunteered to help get out the vote for Bernie Sanders.

Wearing bright red scrubs with the union logo, holding matching red clipboards with pages of voter lists and their contact history, they are knocking on several dozen doors to urge people to take part in an event that could send shockwaves across the national political spectrum if Hillary Clinton, the long-expected favorite, loses to Sanders, as some pundits and pollsters are predicting.

The Clinton campaign opened its first campaign offices in the state last spring, half a year before the Sanders campaign. In January, Clinton's national campaign manager, Robbie Mook, who ran her 2008 race here, told reporters Hillary was 25 percent ahead of Sanders in their polls. But then the Sanders campaign surged and in a few weeks the race has come to a dead heat, powered by a visibly energized Sanders team.

“The reason we are so passionate about coming here, regardless of what state we are in, is Bernie’s message resonates with everyone in the U.S.,” said Reding, an operating room nurse from Bakersfield, Calif. “We are so passionate about the values that Bernie has—caring, compassion and community.”

“This is my first canvas,” said McCall, an intensive care unit nurse at the Veterans Administration hospital in Denver and retired Air Force master sergeant. “He’s passionate about vets. It’s time to make a commitment.”

National Nurses United, with 186,000 members nationally, was the first major union to endorse Sanders. NNU sees his campaign in Nevada as a tipping point, in which a traditionally red state may start turning toward a candidate that shares the union's agenda of a guaranteed health care, living wages, access to public education and college, racial equality, women’s rights and more. In the 2016 campaign, for the nurses, Sanders is the face of that movement.

The Task: Getting Out the Vote

But first Sanders has to win on Saturday, the first round in the state Democratic Party’s caucus process where delegates eventually are sent to the party’s national convention this July. His campaign, like Hillary Clinton’s, is engaged in the slow and steady 11th-hour work to bring out the vote. Both are hoping that every door knocked on, every voter talked to, every flyer left in a mail slot and every neighbor called on the phone will result in a history-making outcome. It all depends on turnout, and a very random survey by this reporter in Las Vegas on Friday found many undecided voters in a key voting block: the 200,000 Nevada Latinos expected to vote this year.

There are many reasons why the national Democratic Party chose Nevada as the first western state to participate in the 2016 election. It is unlike Iowa and New Hampshire in deep and profound ways. The electorate is much more racially diverse, with a large Latino population and other communities of color. The state’s economy is in rougher shape than Iowa and New Hampshire. Its 6.4 percent unemployment is among the highest in the nation. That’s the same level Iowa experienced at the peak of the Great Recession.

Wounds from the housing market crash are still visible, with many boarded-up homes from foreclosures. The statewide economy is 7 percent smaller than it was in 2007. At the same time, Nevada’s two major cities, Las Vegas and Reno, are home to some of the most active labor unions in America, with a rivalry that dates back to the Obama-Clinton race in 2008. Those factors are the backdrop to a presidential contest that’s become a make-or-break marker for each candidate. For Clinton, Nevada was long assumed to be a firewall after Iowa and New Hampshire; if she loses here she will be seen as vulnerable in upcoming states. For Sanders, Nevada is the proving ground to show Clinton can be beaten anywhere and he’s a contender to be the nominee.

The Pressure Is On

Both campaigns know all this and so do their volunteers, who also flocked from out of state to work for Hillary Clinton's get-out-the-vote effort. At the Clinton campaign office in a Las Vegas medical office park, Ava Jourdain, an African American from Berkeley, Calif., was putting labels on bilingual flyers for canvassers to leave with door hangings that afternoon. She was proud to be a loyal Hillary backer in 2008, sticking with her until the very end. She said she had to come help out.

“For myself, Hillary and the entire campaign is saying that Nevada makes a difference,” she said. “They’re saying the minority vote will make a difference. You will see percentages of African Americans and Latinos in those [caucus result] tables. I need to be here to make a difference.”

As Friday’s lunch hour began, more volunteers and supporters from out of state were stepping into this Clinton campaign office in a middle-class section of Las Vegas than Nevadans. That may be because many of the tens of thousands of union workers in the state—who both of the campaigns have courted aggressively—are at work. Everyone who walked into the campaign office was asked if they came to make phone calls or canvas precincts. The Sanders campaign was doing much the same thing, but it was also running training sessions for university and even high school students to participate in and monitor the caucuses.

Both campaigns have been counting on Nevada labor unions to turn out members. For the Nevada Democratic Party, labor unions traditionally provided thousands of campaign workers and millions of dollars for get-out-the-vote efforts. This year, there are quirks. The state’s most powerful union is the Culinary Workers, with 58,000 members in casinos, hotels and related jobs. In 2008, it endorsed Obama. Today, it has remained neutral, not endorsing, and officials who Thursday led a 1,000-plus-person march against a major health insurer, said members were split—though wouldn’t say how. Both Sanders and Clinton showed up within a 15-minute time span on Thursday to wish them well before a televised town hall.

Many Culinary Workers members are Latino, and national groups such as NALEO (National Association of Latino Elected Officials and Appointed Officials) are predicting that upward of 200,000 Nevada Latinos will vote in 2016. How many of those will caucus as Democrats is unclear. It’s well-known among progressive voter registration groups that it’s hard to get students, poorer people and new voters from communities of color to turn out. Another factor that makes Nevada’s polling unpredictable is it has a big transient population—people moving in and out. The state also has same-day voter registration, so people can show up and participate the same day. This reporter’s informal survey of two-dozen Latinos on Friday found many didn’t say they were going, and of those who planned to go, many said they were undecided or were for Clinton, citing her political experience.

Bumps in the Caucus Process?

The caucuses themselves are not entirely straightforward events. Each state party makes up the rules for these town meeting-like proceedings. The rules are a bit different in Nevada than in Iowa. Saturday’s caucuses involve registered voters and eligible voters showing up to vote for their candidate in precincts. In addition to the raw numbers of votes cast, the caucuses elect delegates that go on to county and state conventions. The party awards more delegates to lower population rural areas than to precincts in its cities. In 2008, Clinton won more raw votes at the first stage, but Obama later won more delegates. She got the headlines as the 2008 caucus winner, much to the chagrin of Obama’s team. In this year’s Iowa caucus, that state’s party did not release its raw vote totals, but said Clinton won as she was entitled to a few more delegates than Sanders.

The other factor that could complicate Saturday’s Nevada caucus is there are some vote centers with multiple precincts—and each will have a separate caucus. However, the check-in—where one is admitted as a registered voter or opts to register with the party for the first time—is at one central location. That could be a formula for long lines and delays if turnout is high.

But as Friday’s afternoon ticked by, both campaigns' workers were busy making final plans and then headed to final rallies in big arenas: Clinton with her husband and daughter in Las Vegas, Sanders in an arena in nearby Henderson. What’s clear after talking to volunteers from both campaigns is they are feeling as passionate as they are nervous about what's at stake.

“We are a predominantly female profession,” said Sandy Reding, the OR nurse from Bakersfield. “We are not interested in breaking the glass ceiling at the expense of the class ceiling. It is what we truly believe. We speak from the heart.”

“I have never wavered, I can tell you that,” said Ava Jourdain, the 2008 Clinton supporter who flew in from Berkeley. “She is qualified. There is just no area that she can be challenged on as far as her experience… This is not only about being a woman this time around; it’s because she is the most qualified.”