We’re fewer than 60 days away from a critical Election Day. Control of the Senate hangs in the balance. And two billionaire brothers are spending big to make sure the election goes their way.

I’m talking about Charles and David Koch, radical tea partiers with a lot of money and an extreme agenda designed to boost their bottom lines. They run Koch Industries, a conglomerate known for pushing anti-worker and anti-environment policies. They also run Americans for Prosperity, their dark money super PAC that supports extreme candidates around the country, and they’re using their billions to buy seats in Congress for their Tea Party friends. But that’s only part of the story.

It began in 1980, when David Koch ran for vice president on the Libertarian Party ticket as the conservative alternative to Ronald Reagan, whom he viewed as too liberal. It didn’t go too well, though — the Libertarian candidates earned just more than 1 percent of the vote that year. Rather than try to build a new party, the Kochs decided to take over an existing one so they could turn their fringe ideas into governing ideas and grow their fortune.

First, they built an ideas infrastructure that now directs conservative thinking through think tanks like the Cato Institute and the Mercatus Center. Today, Cato is one of the premier right-wing think tanks in the country, and the Wall Street Journal calls the Mercatus Center “the most important think tank you’ve never heard of.”

Then, in the tea party, the Kochs found their ground troops and changed the game. That’s why the word “compromise” isn’t part of today’s political vocabulary. That’s why politicians on the right won’t even consider coming to the table to work out differences with Democrats. And that’s why we’re seeing fewer and fewer policies that help working families.

The Kochs created an ideological cult of like-minded donors who are on board with their plans to keep giving unnecessary tax cuts to big oil companies, weaken Medicare, and roll back the minimum wage. Their dark money network plans to spend $500 million to flip the Senate this year so they can make these dreams a reality, and they’re going to spend another $500 million to win the White House in 2016.

That’s a lot of money. Why are the Kochs doing this? Partly because they’re true believers in radical libertarianism. And partly because they stand to gain if they have it their way: lower taxes, less regulation, lower pay for their workers and higher profits for themselves. They’re spending big because they know what’s at stake: the future of our country and their own bottom line.

But we aren’t rolling over and letting them have their way. At American Bridge, we are shedding light on the Koch brothers’ political history, business practices, and extreme policy agenda, from the 1980 campaign to today. From their long history of outsourcing jobs and harming the environment to help their bottom line, to digging deep in their own pockets to back Senate candidates in Michigan, Iowa, Arkansas, North Carolina and Colorado, they are trying to reshape the country we know into a place only they would recognize.

We’ve flipped the script on them, made the Kochs a liability for the candidates they back, and it’s working: for the first time ever, Koch Industries is launching a positive PR campaign because we’re doing so much to damage the Koch brand. This is a major success and it shows that the more voters hear about the Kochs, the less they like.

This week, the Kochs are teaming up with their lackeys in Congress to hit Democratic donors who donate, sometimes anonymously, to support candidates who fight for middle class causes. The Kochs are calling them hypocrites because they support groups like American Bridge that call out the Kochs’ spending, but there’s a clear distinction that they’re missing.

Yes, both sides will always have their share of transactional donors, giving for access or ego. But I’ve raised $100 million from progressive donors in the past 10 years, and in my experience our donors give — often against their own economic interests — to advance the shared ideal that have made our country great.

David Brock is founder of American Bridge 21st Century.