Jeffrey Sachs is a professor and director of the Center for Sustainable Development at Columbia University. The opinions expressed in this commentary are his.

(CNN) The federal government's top ethics official has asked the Environmental Protection Agency to take "appropriate actions to address any violations" rising from the behavior of the agency's administrator, Scott Pruitt.

These include a $50 a night room rental agreement with a lobbyist whose husband's firm lobbies the EPA, salary raises Pruitt gave to favored aides and other employees, frequent taxpayer-funded trips back home to Oklahoma — with security entourage -- and reports in The New York Times that Pruitt took punitive action against agency staff after they raised concerns about his actions.

The puzzle here is not how Scott Pruitt could attempt to get away with these things; it is why America's days are filled with dealing with "public servants" like Pruitt — and, of course, Donald Trump, for that matter. They are cheaters, self-dealers, corner-cutters, and liars for personal or professional gain. Why does our political system fail so badly to screen them out? Why, in short, does the swamp spread so relentlessly?

The answer, of course, is that the Pruitts, the Trumps (and the Tom Prices and on and on) are people who serve interests far more powerful and nefarious than they are. Big money has taken over the political system, and hired people like Pruitt to run it on their behalf.

And the big money will triumph as long as the young, the poor, and working class do not register and vote in far greater numbers. That is why our democracy depends so urgently on voters — in the upcoming elections and again in 2020 -- beating back the billionaires who manipulate our politics for their own gain.

The current state of our politics would be risible if the stakes were not so terrifyingly high. Pruitt has made a career of trying to gut any and all environmental protection. Trump is an unprincipled hothead real estate developer and reality TV persona who lost all access to serious capital long ago and so has largely relied on foreign money to keep afloat, as even his sons have reportedly affirmed.

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Yet Pruitt is now in charge of dismantling every barrier between us and environmental ruin, and Trump has the nuclear codes that could end life on the planet.

They both work for larger financial interests. Our country today, and indeed much of the world, is run by and for billionaires actively manipulating the political process. They have the means, power, influence and muscle to get their way.

Trump was elected with the backing of several, including Sheldon Adelson, Carl Icahn, Robert Mercer, John Paulson, T. Boone Pickens and Peter Thiel. And Trump has delivered for them, most importantly by signing into law last December a budget-busting $1.5 trillion tax cut that largely benefits the rich.

Scott Pruitt was backed for his post as EPA administrator by the titans of Big Oil, including billionaires David Koch and Charles Koch , and Pruitt's backer for years, Harold Hamm , chief executive of Continental Resources, an Oklahoma oil and gas company. In return, Pruitt has been systematically attempting to gut every regulatory limit on greenhouse gas emissions and leading the effort to pull the United States out of the Paris Agreement (making the United Stats the only country out of 193 to declare the intention to withdraw).

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As another sure sign of who has the real sway in this country, Saudi Crown Prince Mohammed bin Salman chose to meet at last 10 billionaires on his recent whirlwind US trip: Donald Trump, Bill Gates, Jeff Bezos, Richard Branson, Mike Bloomberg, Stephen Schwarzman, Oprah Winfrey, Sergey Brin, Larry Page and Peter Thiel, among others. If you don't have a net worth of at least a couple billion dollars, you shouldn't be surprised that you weren't on the crown prince's dance card.

Why do the wealthy hire the likes of Pruitt to do their bidding? The main reason is that only individuals lacking a moral compass will carry out the whims and anti-social policies of the plutocrats who seek to manipulate the political and regulatory systems to their will. Suppose you had to tell mega-lies every day, such as that global warming is untrue and that air pollution is not dangerous to public health. Anyone of talent or honesty would recoil from the job. Only an ambitious toady would accept such an ugly assignment.

David and Charles Koch ($60 billion net worth each, according to Forbes) effectively control the Republican Party. Republican incumbents have the choice to take money from the extended Koch network or to face a primary opponent funded by the Koch network.

The party begs financial largesse from the Koch brothers and parrots the idiocies of climate denial on their behalf -- despite record heatwaves, forest fires, hurricanes and this season's loopy winter weather, which scientists say is linked to an overheated Arctic. Money can't turn back the tides, but it can cause adults who know better to deny them.

The United States is not alone in this big-money corruption but perhaps has become its world leader. Democracy around the world is being undermined not by a working-class backlash or resurgent nationalism but by money, a lot of it. With the world's politics awash in money, several world leaders are currently charged with corruption, most recently France's Nicolas Sarkozy, Israel's Benjamin Netanyahu, and South Africa's Jacob Zuma, with two more recently convicted: Brazil's Luiz Inacio Lula da Silva and South Korea's Park Geun-Hye.

In 2010, the Supreme Court, in its ineffable wisdom, declared that corporations could spend unlimited amounts of money to influence elections — that their contributions were free speech and thus beyond limitation. What could possibly go wrong?

Even now, all is not lost. The rich may have the money but the people still have the votes. Yet time is short. November is our best hope to reclaim our democracy from the likes of Pruitt and Trump.