Minutes later, Representative Adam Schiff, the Democratic chairman of the House Intelligence Committee, read Trump’s tweet to Yovanovitch in the hearing room and asked for her reaction to the president’s suggestion that everywhere she went “turned bad.” She smiled and then shook her head. “Well, I mean, I don’t think I have such power,” the diplomat replied.

Schiff praised Yovanovitch—who remains a State Department official—for her “courage” in testifying despite instructions from the Trump administration not to cooperate with the impeachment inquiry. He asked her what effect she thought Trump’s tweet could have on the willingness of others in the government to come forward and expose wrongdoing.

“Well, it’s very intimidating,” Yovanovitch replied.

“Designed to intimidate, is it not?” Schiff asked.

“I mean, I can’t speak to what the president is trying to do, but I think the effect is to be intimidating,” she answered.

The chairman then added: “Well, I want to let you know, Ambassador, that some of us here take witness intimidation very, very seriously.”

Schiff did not elaborate, but witness intimidation is a crime, and it is not a stretch to infer that the Democrats could turn the president’s tweet into one of their articles of impeachment. No less an impeachment authority than Kenneth Starr, the former independent counsel for Bill Clinton’s impeachment who has been dismissive of the case against Trump, called the president’s tweet “quite injurious” on Fox News.

The president is famously not known for his Twitter discipline, although his decision to attack Yovanovitch was a departure from the relative restraint he showed on Wednesday during the testimony of two veteran male diplomats, Acting Ambassador to Ukraine William Taylor and a deputy assistant secretary of state, George Kent. And it may have been an unforced error, because as compelling and sympathetic as Yovanovitch’s testimony had been to that point, it was more damaging to the president politically than legally. Nothing in her story directly added to the Democrats’ core case for impeaching Trump. She was gone from her post before many of the key events in question happened; she was not a participant on the call in which Trump asked Zelensky to do him “a favor” by assisting an investigation into one of his political rivals, former Vice President Joe Biden.

“I’m not exactly sure what the ambassador is doing here today,” wondered Representative Devin Nunes of California, the committee’s top Republican, when it was his turn to question Yovanovitch. “This seems more appropriate for the subcommittee on human resources at the Foreign Affairs Committee.”

Indeed, Yovanovitch’s testimony was somewhat tangential to impeachment. Rather, it was a story of a diplomat scorned, a veteran ambassador abruptly yanked from her post based not on poor performance or policy differences but merely on scurrilous rumors. She defended her reputation as an envoy who fought corruption in Ukraine and told of how “shocked and devastated” she was when Trump criticized and obliquely threatened her on the call with Zelensky.