George Soros bought some Cheez-Its in Las Vegas last week. Across town, Charles Koch paid for a stack of iPads. Tom Steyer hired somebody to dance, dressed as a polar bear.

With the U.S. presidency and control of the Senate in the balance, these billionaires are deploying their own political armies to swing states across the country and supplying them with everything from cutting-edge voter data to salty snacks. Unaffiliated with any candidate or party, these ground troops are staging protests, manning phone banks, and knocking on doors.

While most spending from these groups flows to television ads, some donors have shifted resources this year toward the more labor-intensive work of talking with voters face-to-face. In Nevada, the street brawl is getting unusually personal. Koch and his brother, David, who oversee a national network of conservative groups, have long feuded with the state’s retiring Democratic senator, Harry Reid. They’re now waging a proxy war over his replacement, turning the race into a big-money free-for-all.

Outside groups have spent $45.8 million on the race so far, compared with only $7.1 million by the candidates themselves, Democrat Catherine Cortez Masto and Republican Joe Heck, according data compiled by the Center for Responsive Politics on OpenSecrets.org. That’s the biggest spending imbalance of any of the 10 most expensive Senate races in the country, the data show.

The Supreme Court’s 2010 decision in Citizens United gave big donors a freer hand to influence elections, mostly through super-political action committees that have already set a record for spending this year. In Nevada, labor unions and Soros are up against Republican stalwarts like Sheldon Adelson, the Las Vegas gambling tycoon.

Biggest Money

But so far, the biggest money is coming from the Koch brothers and their network of like-minded donors. One super-PAC funded by their organization, Freedom Partners Action Fund, has spent about $7.1 million on advertising in the Nevada senate race, according to OpenSecrets. That doesn’t count the cost of the ground forces they’ve mustered.

Reid, a Democrat who is the Senate minority leader, has for years sought to turn the Kochs into right-wing bogeymen, accusing them from the Senate floor of "trying to buy America." He’s relishing this final battle.

"They’ve not hidden their feelings about me. I’ve not hidden my feelings about them," Reid said in a phone interview last week from Washington. Reid has dispatched top staff to work for Cortez Masto, and said he plans to bus thousands of volunteers from Arizona and California for a final turnout push before Election Day.

"We have an operation that the Koch brothers can’t buy," he said.

With Republicans holding a 54-46 advantage in the Senate, and several incumbents in tough races, Nevada represents their best chance of flipping a Democratic seat. As of last week, polls showed Heck with a narrow lead, even though Republican nominee Donald Trump trailed Democratic rival Hillary Clinton in the presidential race here. The publication of Trump’s lewd comments about women on Oct. 7 threatened to put him further behind and hurt his fellow Republicans. Over the weekend, Heck joined dozens of Republican candidates in rescinding his endorsement of Trump.

Democrats have a formidable voter-turnout operation in Nevada, thanks in part to an alliance with the union representing casino workers. On Tuesday morning last week, the headquarters of Culinary Union Local 226 roared with the voices of a hundred union members in red T-shirts, folding pro-Democrat flyers before hitting the streets. When early voting begins on Oct. 22, the union will commandeer casino buses to carry voters to the polls.

Since Labor Day, these workers have been doing politics full-time, with their pay covered by the union. (Labor contracts allow them to take a leave of absence from their casino jobs.) According to Yvanna Cancela, its political director, Local 226’s parent organization plans to spend about $3 million on the general election in Nevada this year.

Koch Funding

For its part, the Koch network aims to spend over $200 million nationwide on political activity between last year and this year, making it a force to rival the major parties. The Kochs generally side with Republicans, but decided earlier this year not to back Trump. That leaves the Senate as their top priority.

Since 2014, the network has boosted the size of its grassroots operations across the country by 50 percent, according to James Davis, a Freedom Partners spokesman. That gives it a unique means of communicating with voters about Reid’s successor, he said.

"All he does is launch divisive, blatantly false political attacks rather than debating the issues on the merits," Davis said. "That’s why we’re engaged."

Last week, Marcos Lopez, 22, roamed the west side of town with a Koch-issued iPad in his hands and a water pack strapped to his back. Lopez works for Americans for Prosperity, the biggest and oldest of the Kochs’ grassroots groups. The iPad tells him which doors to rap, and lets him upload notes on each visit in real time.

The iPad leads Lopez and a colleague to Frank, a retiree in his 80s who’s shuffling across the street in moccasins to pick up his mail. They ask him to take part in a "survey," meant to highlight Cortez Masto’s support for Obamacare to voters who dislike the president’s health-care law. The man needs little convincing.

"She’s with that Reid," the man says. "We’ve got to dump her!"

"There you go," Lopez replies. "Remember to go vote sir! You take care, and hey, God bless."

Latino Voters

Later that day, on the east side of town, Ronnie Najarro, 37, bears a message tailored to Latino voters. Najarro is with the Libre Initiative, a newer Koch-funded group that focuses on this growing, and mostly Democratic, slice of the electorate.

At one home, a woman in a Starbucks apron recognizes Najarro. She was one of hundreds of Las Vegans who took a free class from Libre to get a state-issued driver authorization card. Libre also hands out backpacks for schoolkids each September. The aim is to build trust with the Latino community, while pitching the Kochs’ philosophy of free markets and limited government.

At another door not far away, a man named Alejandro, in socks and a "Just Do It" T-shirt, tells Najarro he’ll probably vote Democrat in the Senate race. He sounds less certain after Najarro reads from a script that points out Cortez Masto’s opposition to a state school-choice initiative.

"For president, I believe Hillary Clinton would be better for this country," Alejandro says finally. "For the rest, I want to go and see."

Democrats are hoping that Trump’s inflammatory rhetoric about Mexicans will inspire record turnout among Latinos, who already make up almost one-fifth of the state’s electorate.

They’re getting a push from Soros, a billionaire New York investor and longtime Democratic donor. Last week, a super-PAC he helps fund known as Immigrant Voters Win gathered three dozen canvassers in an office building west of the Las Vegas Strip for a pep talk. A super-PAC official, Francisco Morales, told the group that a poll showing a close presidential race in Nevada assumed that Latinos will make up 18 percent of the electorate.

"How many of you think Latinos are going to turn out in record numbers because of the racism and bigotry of Donald Trump?" he asked. Virtually all the hands shot up. "We think with your help we’re going to break that number. Make it 20 or 21 or even 19 percent. That basically means you’ve won."

Recruiting Friends

The canvassers make $15 to $18 an hour, plus a $50 bonus if they recruit a friend. One of them is Juliette Milano, 24. She said she’s from Venezuela and is applying for asylum, so she can’t vote. But she left her job as a receptionist in an auto shop this year to join the super-PAC. "When Trump started to run, it got to a point where I couldn’t just watch," she said.

After decrying the influence of big money during the Republican primaries, Trump is getting far less help than Clinton from outside spending groups. Still, some donors are mounting a last-ditch spending blitz to narrow the gap. Key to the effort may be Adelson, who runs a global casino empire from his office inside the Venetian Resort Hotel Casino on the Las Vegas Strip. Adelson and his wife are already a major force in the Senate contests, having given $20 million to a Republican super-PAC focused on those races.

Adelson offered to spend $100 million earlier this year to help elect Trump, but the most recent federal spending records don’t show if the spigot has opened yet. News reports in recent weeks have said Adelson planned to spend $5 million or $25 million on pro-Trump advertising. Ron Reese, a representative for Adelson, declined to comment.

Trump himself buzzed into town last week, drawing a crowd of about 7,000 people for a rally in the Las Vegas suburb of Henderson. He also drew a few protesters, including Peyton Olsen, 23, of NextGen Climate. Olsen’s group is funded by Steyer, another billionaire investor, and focuses on mobilizing college students to fight global warming. NextGen is making grassroots organizing a bigger focus this year after an advertising-heavy campaign in 2014 failed to prevent a Democratic rout in Congressional races.

Outside the Trump rally, Olsen was dancing in a polar bear costume and holding a sign saying, "Climate Change is a Hoax - Donald Trump." Next to her was a life-size cutout of Heck, his pockets stuffed full of Koch brothers’ cash.

Trump himself hasn’t built much of a ground campaign in Nevada or other swing states, opting to rely on the Republican Party and on the enthusiasm of people like Julie Brock.She was among dozens of Trump fans who arrived too late to enter the rally site in Henderson. Instead, they lined up along a fence where they could hear but not see him. Brock slipped through this crowd in a "Hillary for Prison" T-shirt, handing out fake million-dollar bills with Trump’s picture on them.

Brock said she’s a registered Democrat and isn’t working with the Trump campaign or any other group. A friend bought the Trump bucks on Amazon.com. After losing a landscaping business and a multimillion-dollar house to the recession, Brock said she’ll do whatever she can to support Trump because only he can revive the country’s economic fortunes.

"He’s cocky," she said. "And in the business world that’s how you have to be. He’s going to get it done."

This article was provided by Bloomberg News.