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 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.