For the past three years, Nunes has used his perch on the Intelligence Committee—first as chairman and now as ranking member—to do Trump’s bidding. That continued this morning, as he used his question time to try to get first Williams and then Vindman to publicly identify the whistle-blower whose complaint set off the investigation that has become an impeachment inquiry into the president. Nunes asked both witnesses whether they had spoken with anyone in the press about the call. Both replied that they had not. Nunes then asked who inside or outside the White House each of them had spoken with in the immediate aftermath of the July 25 call between Trump and Zelensky. Williams replied that she had spoken with no one about it, so Nunes quickly moved on to Vindman, and that’s where it got interesting.

Read: Take it from me, the attacks on Vindman are disgraceful

“Yes, I did,” he replied. “My core function is to coordinate U.S. government policy, and I spoke to two individuals with regards to providing some sort of readout of the call.” Both, he explained, were “cleared U.S. government officials with the appropriate need to know.”

Vindman said one of those individuals was Kent, the deputy assistant secretary of state who testified last week. The other was “an individual in the intelligence community.”

When Nunes asked him to identify that person, Committee Chairman Adam Schiff interjected. “We need to protect the whistle-blower,” the Democrat said. “Please stop. I want to make sure that there is no effort to out the whistle-blower through these proceedings.”

He advised Vindman to be careful, and Vindman listened. After consulting his lawyer, he said he had been advised “not to answer specific questions about members of the intelligence community.”

After another minute of protest, Nunes moved on, but his ally Representative Jim Jordan of Ohio later took up the same line of questioning, with a similar result.

Both Schiff and Vindman have said they do not know the identity of the whistle-blower, but the exchange left little doubt that the person Vindman spoke with in the intelligence community is the one who ended up filing the initial complaint. The whistle-blower’s employment in the intelligence community was established in the complaint, which also said that the whistle-blower had heard about the July 25 call from multiple officials in the White House.

As of this writing, Nunes and Jordan were not successful in their efforts to out the whistle-blower, but their very public attempt—like the many tweets Trump has sent criticizing the person—could have a chilling effect on future whistle-blowers, who must decide whether to report wrongdoing up the chain of command. Indeed, that may have been the intent of the GOP effort.

Vindman did not file a formal whistle-blower complaint, but he did report his concerns about the Trump-Zelensky call and other meetings involving Ukraine to lawyers in the National Security Council. His appearance and testimony this morning made plain the risks he faced in doing so. Vindman is a decorated military veteran who was wounded serving the nation in Afghanistan, and is still currently serving in the White House even as he testifies against the commander in chief. Conservative loyalists of the president have used Vindman’s Ukrainian heritage—his family fled the Soviet Union for the United States when he was 4 years old—to question his loyalty. Shortly before the hearing began, The Wall Street Journal reported that the Army had made preparations to move Vindman and his family to a military base to secure their physical safety if necessary. And while the hearing was going on, the White House issued a tweet undermining the credibility of one of its own employees. The GOP committee counsel, Steve Castor, pressed Vindman to detail offers he rejected to become Ukraine’s defense minister. “I immediately dismissed these offers, did not entertain them at all,” he replied.