In March of 1974, as a young state attorney general, I reluctantly called for President Richard Nixon’s resignation amid revelations of abuses of power related to Watergate. It wasn’t an easy thing to do. As a Republican, I didn’t enjoy breaking with my party or my president. As an elected official and practical politician, I didn’t particularly enjoy the implications of turning against someone who had comfortably carried Washington State just two years earlier. None of it was pleasant, but I believed it was the right thing to do on the facts and on the merits.

John Adams said, “Facts are stubborn things.” Forty-five years after Mr. Nixon resigned before he could be impeached by the House, the facts should be the focus of every elected official, Republican or Democrat, as they decide what to do about another president facing impeachment and a possible Senate trial.

To my fellow Republicans, I give this grave and genuine warning: It’s not enough merely to dismiss the Ukraine investigation as a partisan witch hunt or to hide behind attacks against the “deep state,” or to try to find some reason to denounce every witness who steps forward, from decorated veterans to Trump megadonors.

History demands that we all wrestle with the facts at hand. They are unavoidable. Fifty years from now, history will not accept the position that impeachment was a referendum on the House speaker, Nancy Pelosi. It must be a verdict reached on the facts.