On Friday afternoon, James Baker, the former general counsel of the F.B.I., felt a tinge of optimism. Almost two years ago, he was ousted from his position as the Bureau’s top legal official, after President Trump fired the F.B.I.’s director, James Comey. Baker, a career Justice Department official and a longtime Comey ally, had approved the F.B.I.’s Trump-Russia investigation and the monitoring of a former Trump campaign adviser’s communications. Trump welcomed the news of Baker’s removal in a tweet: “Wow, ‘FBI lawyer James Baker reassigned.’ ” In subsequent tweets and retweets, the President accused Baker of lying to Congress and being part of an “Unconstitutional Hoax” and an “attempted coup.”

Baker considered Trump’s claims about him to be completely false, but he said nothing publicly at the time. (The Republican-controlled Senate Intelligence Committee investigated the origins of the F.B.I.’s Trump-Russia investigation and found no wrongdoing.) “I believed that, once I was out of the F.B.I., I could resume a normal life and avoid the spotlight,” he told me last week, in his office at the R Street Institute, a conservative and libertarian think tank, where he directs the national-security program. “But that was inaccurate, because the damage had already been done by the President’s tweets and stories about me on Fox News and other outlets.” Baker, once considered one of the government’s most trusted national-security officials, found that Trump’s attacks impacted his ability to find a job. “Certain corporations and law firms thought that I was too controversial and didn’t want to hire me,” Baker recalled. “It surprised me and was dispiriting.” Over time, he became convinced that Trump was improperly using his powers as President to maintain his hold on power. Baker decided to push back. “At a certain point, I became unafraid of Donald Trump,” he said. “I felt, O.K., I can speak out. And also, I have an obligation to speak out.” In May, Baker began publicly attacking what he called Trump’s “false narrative that there was a coup, and a conspiracy, and treason.”

On Friday, Baker lauded Marie Yovanovitch, a career foreign-service officer and the former U.S. Ambassador to Ukraine, who also decided to push back against Trump. During nearly nine hours of closed-door testimony before the House Intelligence, Foreign Affairs, and Oversight committees, Yovanovitch responded to months of attacks from Trump and his allies. In a blistering opening statement that was released to the press, she said that Trump had pressured State Department officials to remove her from her ambassadorship based on made-up allegations. “Although I understand that I served at the pleasure of the president,” her statement read, “I was nevertheless incredulous that the U.S. government chose to remove an ambassador based, as best as I can tell, on unfounded and false claims by people with clearly questionable motives.” Sean Maloney, a Democratic congressman from New York, said that, during the hearings, Yovanovitch grew visibly upset as she gave a “gripping and emotional account of abuse of power by the President.”

More potentially damaging testimony is expected this week, as House Democrats continue the impeachment inquiry that they launched after a U.S. intelligence official filed a whistle-blower’s complaint regarding Trump’s dealings with Ukraine. On Monday, Fiona Hill, who served as the top Russia expert in Trump’s National Security Council, is expected to testify that Trump’s personal lawyer, Rudy Giuliani, circumvented the normal White House process to pursue a shadow foreign policy in Ukraine. On Thursday, Gordon Sondland, a donor to Trump’s Inauguration committee who was named U.S. Ambassador to the European Union, is expected to testify that he does not know if Trump was telling the truth when he denied withholding U.S. military aid to pressure Ukraine’s President to investigate Joe Biden.

Baker told me that Trump’s failure so far to discredit the whistle-blower had weakened his power to silence current and former officials. “He tried to smash the whistle-blower, and it didn’t work,” Baker said. “One of the things that Donald Trump has trafficked in is fear. And, once people are no longer afraid of him, I think more people will come forward.”

According to Chuck Rosenberg—a career federal prosecutor who served as a senior adviser to Comey and Robert Mueller at the F.B.I—the President’s public attacks are a calculated effort to pressure government officials. Rosenberg, who served as the acting director of the D.E.A. in the Trump Administration but resigned, in 2017, told me that the President’s repeated denunciations of Mueller and his team were designed to hamper the investigation into Russian interference in the 2016 election. Rosenberg said that Trump’s smears did not impact the probe’s findings, but did increase the pressure on Mueller. Trump may lack a sophisticated understanding of the federal government, Rosenberg warned, but the effectiveness of his public diatribes should not be underestimated. “I think it’s very intentional,” he said. “You can be not well read in a classic sense but very cunning and successful as a street fighter.”

Trump seems likely to continue to declare any current and former officials who criticize him part of a secret cabal trying to remove him from office. After the Times reported that Giuliani was under criminal investigation for possibly breaking lobbying laws in his dealings with Ukraine, Trump tweeted, “Such a one sided Witch Hunt going on in USA. Deep State. Shameful!” A former National Security Council aide, who asked not to be named, scoffed at Trump’s claim of a plot. The aide described the vast majority of State Department officials as loath to publicly criticize a President and as “risk-averse.” “It has to be really bad for people to speak out,” the former aide said. “It’s a mentality—‘don’t break anything.’ ”

The likelihood that the testimony of Yovanovitch or other government officials will significantly undermine Trump’s messaging is low. The President’s willingness to traffic in conspiracy theories, and to play on Americans’ long-running suspicions of government, together with his vast social-media following give him far more power to sway public opinion. Baker, though, believes that it is worth trying to counter Trump’s narrative. As part of his personal effort, he published an essay, in May, on the Lawfare Web site: “Why I Do Not Hate Donald Trump.” In it, he argues that deriding the President and his supporters is the wrong tactic. Instead, citing Martin Luther King, Jr.,’s “Letter from a Birmingham Jail,” Baker suggests responding with grace, decency, and fact. He concedes that this approach may strike many as foolish or naïve. “All I know is that I have a small grain of sand that I can contribute to the effort, and I want to put it on the right side of the scale,” he told me. “If many people do that, then it can make a difference.” He commended Yovanovitch, saying, “She’s taking a risk and putting her grain of sand on the scale. It sounds like she is pursuing the truth with the goal of helping protect the American people and upholding the Constitution.”