In July 2017, Joel Clement, formerly the director of the Office of Policy Analysis at the Interior Department, filed a whistle-blower complaint alleging that the administration had reassigned him to an accounting position in retaliation for publicly speaking out on the potential dangers of climate change to Alaska Native communities.

In August, Lewis Ziska, a veteran plant physiologist with the Agriculture Department, quit in protest over the administration’s efforts to bury his findings about the negative impact of rising levels of carbon dioxide on the nutrient content of rice. “You get the sense that things have changed, that this is not a place for you to be exploring things that don’t agree with someone’s political views,” Mr. Ziska told Politico at the time. “That’s so sad. I can’t even begin to tell you how sad that is.”

With an impeachment inquiry underway in the House, the risks of breaking ranks with the president are higher than ever. Mr. Trump prides himself on punching back against perceived enemies, publicly suggesting that “spies” and “traitors” and people who turn “rat” deserve to have their lives and their families destroyed. Small wonder that few congressional Republicans have dared express even gentle concern over Mr. Trump’s increasingly erratic behavior.

But still the patriots come. Top of the list, of course, is the still-anonymous whistle-blower who touched off the impeachment drama by registering his concerns about Mr. Trump’s clandestine effort to pressure Ukraine into conducting investigations that would benefit his re-election campaign. The concerns enumerated in the complaint have since been verified and magnified by multiple administration insiders, despite the White House’s stonewalling mandate.

On Monday, Congress heard from Ms. Hill, the former top national security adviser on Russia and Europe , who detailed how Mr. Trump had done an end run around his own national security team, putting Ukraine policy in the hands of unqualified dilettantes like Gordon Sondland, whose $1 million donation to the Trump inaugural basically bought him the title of ambassador to the European Union, and Rudy Giuliani, the president’s personal lawyer and favorite henchman.