With mega-donors already pledging to spend hundreds of millions in the 2016 presidential race, tackling the ever-growing problem of big money in politics can feel like a tall order.

But with just the stroke of a pen, there’s something President Barack Obama can do today to help fix the problem. He can issue an executive order requiring the pol​itical spending of government contractors, which includes many of our country’s biggest corporations, be disclosed.

Corporations that receive large government contracts, including Exxon Mobil, AT&T and Lockheed Martin, can funnel limitless sums of money to help elect leaders who can influence decisions on contracts. Most disturbingly, they can do it in secret through “dark money” groups that don’t have to disclose their donors.

An executive order would expose this spending to the light of day and allow the public to follow the money. It would help restore a democratic process that all Americans can believe in. Voters would know which corporations are trying to buy political influence and could call them out on it.

After all, government contracts provide funding for critical services and should go to companies best-suited to do the work, not those that can best game the system.

Ordinary people, no matter their political affiliation, are fed up with our rigged system, according to most polls, and ready for change. Three in four Americans are not happy with the way our political system works, and seven in 10 say our elections are tilted toward the candidate with the most money.

Since the Citizens United decision that paved the way for unlimited outside spending, more than $600 million in spending from dark-money groups has already flooded our federal elections. In the 2014 midterms, dark money made up nearly three-quarters of the total outside spending in support of the winning candidates in the most competitive Senate races. We know that $600 million speaks louder and is more likely to be heard than our own voices as constituents. Even if, when it speaks, it doesn’t always identify itself.

Obama has indicated that he’s ready for change, too. It was clear in his State of the Union address in January, when he called for “a better politics” in our country, one “where we spend less time drowning in dark money.”

An executive order would have a prompt, real and lasting impact on the creation of that “better politics.” Any effort by Congress to overturn it would presumably be met with a presidential veto.

In addition, the U.S. Supreme Court has underscored not just the constitutionality but also the importance of the disclosure of political spending. Justice Anthony Kennedy wrote about just this in his majority opinion for the Citizens United ruling in a section that eight of the nine justices joined — all but Clarence Thomas. The court noted that transparency allows voters to “make informed decisions and give proper weight to different speakers and messages.”

Given this near-consensus across ideologies, it’s hard to imagine a legal challenge would hold water.

At the end of the day, all dark money is concerning. But when it’s from a federal contractor and could be used or perceived to be used in an attempt to sway the contract-award process itself, it’s particularly alarming.

Shining a light on this kind of money would let Americans see if their taxpayer money is going to a contractor that’s right for the job — or one most able to make political contributions. It would also set an example for officials at the local and state levels now grappling with these issues.

Obama can do more than describe his vision for a “better politics.” He can, and should, do what he can to help make it real.

When corporations are trying to buy favor with our political leaders, Americans deserve the opportunity to hold them accountable.