(CNN) Hillary Clinton is wrapping up a three-day swing through Nevada as she works to fortify a firewall there, while Bernie Sanders tries to break through in the first test of whether his "political revolution" extends to states with more significant minority populations than Iowa and New Hampshire.

The state's Democratic electorate -- 40% non-white and including a heavy union presence spread across a vast, difficult-to-organize territory -- provides the first true test of both candidates' national viability and battle plans.

For Clinton, Nevada is an opportunity to prove her strength with minorities and demonstrate how a six-month organizing head start can put the lid on her upstart opponent.

During a three-day trip through the state, Clinton also road-tested a new argument -- that Sanders' one-note economic message won't end challenges like racism, sexism and other forms of discrimination -- ahead of South Carolina's primary and Super Tuesday, when many more delegates will be awarded.

"Not everything is about an economic theory, right?" Clinton rhetorically asked the crowd Saturday in Henderson. "If we broke up the big banks tomorrow -- and I will, if they deserve it, if they pose a systemic risk, I will -- will that end racism?" she said as the crowd answered "no."

"Will that end sexism? Will that end discrimination against the LGBT community? Will that make people feel more welcoming to immigrants overnight?" Clinton asked. "Would that solve our problem with voting rights and Republicans who are trying to strip them away from people of color, the elderly and the young?"

For Sanders, Nevada offers a chance to show that enthusiasm trumps organization, that he appeals to non-white voters as much as he does to white voters in Iowa and New Hampshire.

"We think Bernie has a very powerful story with Latino voters," said Sanders' senior strategist, Tad Devine. "It's a story of a guy whose father came to the United States as immigrant who spoke very little English. It's the story of a life shaped by his activism in college."

He'll also attempt to demonstrate his case that union membership is broadly behind him. Sanders has long argued on the campaign trail that rank-and-file members of left-leaning groups like unions are strongly behind him, no matter what those groups' leaders might do.

"We've seen, across the board, across the country, that the rank-and-file membership of these different groups are overwhelmingly with Bernie," said his Nevada spokeswoman, Rania Batrice.

The Las Vegas Strip will give Sanders his best chance yet to prove that argument: Nevada allows same-day registration and allows casino workers to caucus anywhere -- which means they could all go from work, rather than returning home for caucuses that take place at 11 a.m. PT Saturday.

As the only stop before South Carolina's key February 27 primary, the state's outcome will play a key role in determining the race's direction. After a narrow win in Iowa for Clinton, and a historic victory for Sanders in New Hampshire, the national polls show the race turning into a dead heat: Quinnipiac University's latest survey has Clinton up just 44% to 42%.

Clinton's ground game

Clinton's campaign has invested in Nevada from the beginning, dispatching a handful of organizers and aides to be on the ground when the former secretary of state launched her campaign in April 2015.

Sanders hired his first Nevada staffer in October, a fact that Clinton organizers on the ground point out eagerly.

"On the ground, it is really difficult to compare 30 years to 30 days," Emmy Ruiz, Clinton's state director, said in an interview. "And that is something we keep hearing from different communities. They have been with her since day one."

Ruiz is a veteran of Clinton's 2008 Nevada operation, when she won 51% of the popular vote against Barack Obama, who came away with more delegates. That operation was headed by Robby Mook, who is now Clinton's campaign manager.

Clinton currently has seven offices in the state -- Las Vegas, Henderson, East Las Vegas, Pahrump, Reno, Carson City, Elko -- and has more than 7,000 volunteers who have engaged with the campaign, meaning they have either knocked doors, made phone calls, or helped with a community event.

For the last week, Clinton's staff has been combing their voter lists, making sure that the state's transient population is accounted for when they ask people to support Clinton.

"We are going into the caucus with a really serious list," said Jorge Neri, Clinton's organizing director in Nevada.

The campaign has also begun training bilingual precinct captains in an effort to ensure Nevada's Spanish-speaking population is fully aware of how to go about the caucus.

Push for union voters

The state's Democratic caucuses also feature a hefty union presence -- particularly the Culinary Workers Union, with a Las Vegas-based chapter featuring about 57,000 members.

The union endorsed Obama over Clinton in 2008, but Clinton actually won a majority of its rank-and-file members' support. This time, the union has not endorsed a candidate.

Because of its importance, both campaigns are working to appeal to union members. But Sanders' campaign ran in to trouble last month when staffers posed as union workers in order to gain access to members.

Sanders has 12 field offices in the state, plus "several thousand" volunteers, Batrice said. He also has 200 paid staffers on the ground in the Silver State.

She said Sanders' later start organizing the state has been bolstered by young volunteers, many of whom she said are Latino. "We have this incredible field staff, they are just second to none, and they have done a phenomenal job," she said.

Nevada Democrats say Sanders' biggest advantage comes in the northern part of the state, where his campaign's outreach to the whiter-than-Las Vegas electorate has shined.

Sanders dwarfed Clinton on the airwaves until recent weeks -- and while Clinton has caught up, Sanders still holds nearly a 2-to-1 edge.

Sanders launched a new spot Friday in Nevada, featuring Lucy Flores, a former state assemblywoman now campaigning for Congress, according to tracking service CMAG/Kantar Media.

"This is a system that isn't working for the everyday person. It's one of the reasons why I decided to endorse Bernie Sanders," she says in the spot. "Nevadans are looking for people who are willing to think big, to be bold and to fight for everyday people."

Clinton lowering expectations

Since losing in New Hampshire, Clinton's campaign has been trying to lower expectations in the Silver State, citing the fact that some of their models show a whiter electorate than one would expect in a state with a large number of Latino and African-American voters.

"There's an important Hispanic element to the Democratic caucus in Nevada. But it's still a state that is 80% white voters," Clinton spokesman Brian Fallon said on MSNBC last week. "You have a caucus-style format, and he'll have the momentum coming out of New Hampshire presumably, so there's a lot of reasons he should do well."

But that assertion -- that 80% of the state's electorate is white -- appears to apply only to the general election, Nevada Democrats said.

"They downplayed Nevada so much that I wondered, what do they know that I don't?'" said one unaffiliated Democratic operative who knows Nevada.

JUST WATCHED Senator Reid talks Hillary, Bernie and Trump Replay More Videos ... MUST WATCH Senator Reid talks Hillary, Bernie and Trump 03:56

Even Senate Minority Leader Harry Reid -- the godfather of Nevada Democratic politics, who is holding off on endorsing a candidate until after the caucuses there -- mocked Clinton's campaign over its 80% comment.

"Well, it appears to me they've been reading one of the old yearbooks from my high school," Reid told CNN's Manu Raju last week. "They're way behind times."