Judge Gorsuch’s similarities to Justice Scalia extend into several areas of the law. Since his appointment in 2006, by President George W. Bush, he has voted consistently in favor of religious-liberty claims, such as requests for exemptions for private companies and religious nonprofits that oppose the Affordable Care Act’s contraceptive mandate.

He is even more conservative than Justice Scalia in at least one area — calling for an end to the deference courts traditionally show to administrative agencies, like the Environmental Protection Agency, that are charged with implementing complex and important federal laws.

Given the events of recent days, senators should press Judge Gorsuch on how he would approach constitutional questions that have already arisen out of Mr. Trump’s actions as president, like his order barring refugees and immigrants from seven Muslim-majority countries, or his alleged violation of the Emoluments Clause of the Constitution.

While Judge Gorsuch’s views on abortion are not known, he has written extensively about assisted suicide and euthanasia. In his book on the topic, he wrote that “human life is fundamentally and inherently valuable, and that the intentional taking of human life by private persons is always wrong.” By himself, Judge Gorsuch would not upset the court’s balance on abortion rights or affirmative action, but if one of the more liberal justices or Justice Anthony Kennedy step down during Mr. Trump’s presidency, a solidly right-wing majority could quickly overturn those precedents.

Supreme Court nominations are among the most important decisions a president makes, and certainly the most enduring: A nominee like Judge Gorsuch could sit on the court for more than three decades. At a rally last summer Mr. Trump said: “Even if you can’t stand Donald Trump, you think Donald Trump is the worst, you’re going to vote for me. You know why? Justices of the Supreme Court.” That may have played well on the campaign trail, but Mr. Trump’s failure to choose a more moderate candidate is the latest example of his refusal to acknowledge his historic unpopularity and his nearly three-million-vote loss to Hillary Clinton. A wiser president faced with such circumstances would govern with humility and a respect for the views of all Americans.