Since at least spring 2018, Mr. Parnas and Mr. Fruman had pushed for Ms. Yovanovitch’s ouster.
The effort gained traction this spring when figures in the conservative news media claimed without evidence that Ms. Yovanovitch had privately disparaged Mr. Trump, and also cited the allegations by the Ukrainian prosecutors.
A letter to the State Department from two senior Democratic lawmakers in the House dated April 12 — just days before Ms. Yovanovitch was ordered to leave her post — said they were concerned by “outrageous efforts by Ukrainian officials to impugn” her. Ms. Yovanovitch, a career official, has served as an ambassador for Republican and Democratic presidents.
The reply from the agency, dated June 1, left the impression that Ms. Yovanovitch departed her post on May 20 because she had been scheduled to rotate out after three years, rather than indicating that she had been forced to leave.
The documents also include a letter dated April 5 from six former United States ambassadors to Ukraine to top State Department officials under Mr. Pompeo. In the letter, the former ambassadors said that they were “deeply concerned” about the charges against Ms. Yovanovitch that had emerged in the news media reports and that the accusations were “simply wrong.”
In late March, Ms. Yovanovitch told the third-ranking State Department official, David Hale, that she felt she could no longer continue in her role unless the department issued a statement in her defense. Mr. Hale briefed Mr. Pompeo about the conversation the next day, he testified to House investigators last week.
After looking into the right-wing campaign against Ms. Yovanovitch — even contacting Sean Hannity, the Fox News personality, to ask for details of wrongdoing — Mr. Pompeo believed that “there was no evidence” to support the allegations, Mr. Hale said in an earlier private testimony to lawmakers. But Mr. Pompeo ultimately chose not to issue a statement of support. (Mr. Hannity has denied any such call.)
John Sullivan, the deputy secretary of state, told senators last month that top State Department officials were aware of the smear campaign against Ms. Yovanovitch. Mr. Sullivan said he believed Mr. Giuliani was behind it.