In the fall of 2015, when I first spoke on the Senate floor, I gave Nebraskans and every member of this body my word that I would speak up when a Republican president exceeded his or her powers.

At that moment, the Democratic president had taken to himself powers that the Constitution had not given him. My opposition was not that President Barack Obama was a Democrat, but rather that our brilliant Constitution intentionally separates executive and legislative powers.

I gave my promise then because, despite the lazy partisan rhetoric of the city, not everything is actually a blood feud between Republicans and Democrats. That’s because American politicians at our best are acutely aware of the difference between justice and strength.

That’s because when our body is working well here in the Senate, we take seriously our history, our duties, and our unique place in the Constitution’s architecture of separate powers, both vertically and horizontally.

In 2014, the Supreme Court ruled that the Obama administration had made unconstitutional appointments when it declared this body to be in recess when the Senate was not in fact in recess and it functionally claimed power—that is the administration functionally claimed power—that belongs to the Senate under our Constitution.

So today, I’ve come to keep my promise and to offer a word of humble advice to the president. If you’re thinking of making a recess appointment to push out the attorney general, forget about it.

The presidency isn’t a bull, and this country isn’t a china shop.

Mr. President, you’re a public servant in a system of limited government with a duty to uphold and to defend and to teach to our kids the constitutional system of checks and balances.

This is the world’s greatest experiment in self-government. It works only if all of us—presidents, senators, Republicans, Democrats, independents, and judges—keep our faith to the American institutions and to the rule of law.

Our oath is not to popularity, it’s not to polls, it’s not to political parties. Our oath is to the Constitution and to the rule of law.

Our duty is to the American people, the men and women who elected us, the men and women who came before us, and especially the men and women who will come after us in this greatest of experiments in self-government.

This article is adapted from remarks Sen. Ben Sasse delivered on the Senate floor.