To the Republican members of the U.S. Senate:

You have always told us that you believe in the distinctive greatness of the United States of America. “America is different,” as Sen. Marco Rubio has said. Ben Sasse likes to say that “America is an idea” — a commitment to universal dignity over brute power.

You have also told us that you went into politics to serve a higher purpose. Well, your moment has arrived.

The president of the United States is betraying his oath of office in the most fundamental way, by using the presidency for personal gain at the country’s expense. He has corrupted our foreign policy with grubby attempts to help himself that his own White House staff immediately recognized as improper. He is telling the world that America does not, in fact, stand for any higher ideal. Can you for a moment imagine the icons of your party, like Ronald Reagan or Dwight Eisenhower, risking the security of a country threatened by Russia, for the sake of smearing a political rival?

President Donald Trump must go, and you — only you — have the power to make it happen.

You can start to distance yourself from him slowly, if it will help bring along your political base. A couple of you — like Pat Toomey of Pennsylvania, who called Trump’s behavior “inappropriate,” and Mitt Romney of Utah, who used the word “troubling” — have begun to do so. But more of you should be moving in this direction, for the sake of the country and, ultimately, yourselves.

During the Watergate scandal, George H.W. Bush and other leading Republicans initially defended Nixon, too. They did not do so forever. They didn’t want their own legacies and careers to go down with his.

And here’s the thing: You have a very good alternative. I don’t personally share Mike Pence’s worldview, but you do. He is a deeply conservative, anti-regulation, anti-tax, evangelical Christian. As a bonus, he has never paid hush money to a porn star or made big campaign donations to New York Democrats. Oh, and Pence has a lower disapproval rating than Trump.

The notion that America is different — a “light unto the nations” and “the shining city upon a hill,” in Reagan’s words that you so often quote — happens to be true. Some liberals may not buy it. Trump certainly does not; he called our country “a hellhole.” But you are correct when you say that America stands for something. Now you can show the world that you mean it.

With this mind, I have a few specific questions to pose, respectfully, to several of you:

Sen. Rubio, you’ve said, “When America fails to lead, global chaos inevitably follows.” You have criticized politicians who “appease our enemies,” “betray our allies” and are “passive in the face of” Russian aggression. You said all of these things before Trump took office. Which of them do not apply to him?

Sen. Sasse, you have offered yourself as a voice of conservative conscience, imploring people to make hard, principled choices over convenient, self-serving ones. You have written a book arguing that today’s Americans need to grow up.

“Throughout our history, our wisest statesmen have warned that America’s greatest risk has never been attack from abroad but rot from within,” you wrote. “This exceptional nation cannot endure by mere inertia.” Sen. Sasse, do you believe that defending Trump is the principled thing to do?

Sen. Joni Ernst, as a student at Iowa State University in the late 1980s, you traveled to the Soviet Union — Ukraine, to be specific — on an agricultural exchange program. The suffering you saw there made you understand how much you loved the United States and inspired you to join the Army. How do you feel about a president who is willing to undermine Ukraine’s military, which is now fighting a proxy war against its old master, Russia, for purely selfish reasons?

Sen. Josh Hawley, in your maiden Senate speech this year, you said: “I pledge to my fellow Missourians that I will work at this task with all the strength that God can give me. And I will serve without fear and without favor to any man.” Senator, do you fear the president?

Sen. Susan Collins, you represent the state of Maine. All available evidence suggests that your constituents are disgusted by Trump’s pattern of behavior and want a president who is not manifestly unfit for office. Senator, do you serve the people of Maine? Or Donald Trump?

Sen. Cory Gardner — and, I’m sorry, this is going to sound familiar — you represent the state of Colorado. All available evidence suggests that your constituents are disgusted by Trump’s pattern of behavior and want a president who is not manifestly unfit for office. Senator, do you serve the people of Colorado? Or Donald Trump?

Sen. Lamar Alexander, your hero and mentor is the late Howard Baker, who held the same Tennessee seat that you now do. In the early stages of Watergate, Baker stood by Nixon and even privately promised to protect him. But Baker had his limits and ultimately stood up to the president when other Republicans were scared to do so. In your 2014 eulogy of Baker, you eloquently listed his strengths, including: “He demonstrated courage.”

Sen. Alexander, you will be retiring soon, ending a distinguished career in which you have served as a governor, Cabinet member and now senator. Will you honor your mentor by summoning the same courage that he did?

Senators, I know that many of you now feel helpless — repulsed by this president and yet afraid that any criticism of him will end your careers. But his support is shallower than it seems, and you have more power than you may realize. If even a handful of you began speaking out, you would instantly transform this situation and begin to end our long national nightmare.

America is better than this, isn’t it?