Ex-Trump Aide Fiona Hill to Testify on Pressure to Oust Ambassador to Ukraine

She turned over her duties to her successor on July 15 and left on July 19, just days before the July 25 telephone call in which Mr. Trump pressed President Volodymyr Zelensky of Ukraine to investigate conspiracy theories about Ukrainian help to Democrats in the 2016 election and supposed corruption by former Vice President Joseph R. Biden Jr.

Ms. Hill is prepared to testify that she opposed the idea of the phone call because she did not understand its purpose. While it was described as a congratulatory call following parliamentary elections in Ukraine, Mr. Trump had already made a congratulatory call to Mr. Zelensky in April following his own election.

Ms. Hill will testify that while she was the president’s top adviser on Russia and Ukraine, she was cut out of the loop as Mr. Giuliani and others ran a shadow diplomacy intended to benefit Mr. Trump’s political position, according to the person informed about her account. She was not told, the person said, that Mr. Trump would use the call to press for an investigation into Mr. Biden.

Her testimony will not establish a quid pro quo between Mr. Trump’s pressure for investigations and his decision to withhold $391 million in American assistance to Ukraine, the person said. But she will confirm that the administration leveraged a coveted White House invitation for Mr. Zelensky to a commitment to investigate corruption, which was seen as code for investigating Democrats.

Ms. Hill took her objections to the treatment of Ms. Yovanovitch, who was targeted by Mr. Giuliani and conservative media outlets, to John R. Bolton, then the national security adviser, as well as others. Mr. Bolton shared her concerns, according to the person, and was upset at Mr. Giuliani’s activities, which she viewed as essentially co-opting American foreign policy toward Ukraine.

Ms. Yovanovitch, a 33-year veteran of the foreign service who served under Republican and Democratic administrations, including three times as an ambassador, told House investigators last week that she was abruptly told to get “on the next plane” home last spring, ending her tour in Ukraine.

While the deputy secretary of state told her she had “done nothing wrong,” her removal, she testified, appeared to be based “on unfounded and false claims by people with clearly questionable motives,” a reference to Mr. Giuliani and some of his associates.

Two associates of Mr. Giuliani were arrested on Thursday on campaign finance charges connected to their efforts to push Ms. Yovanovitch out. They raised money for Pete Sessions, then a Republican member of Congress from Texas, and Mr. Sessions then pressed Secretary of State Mike Pompeo to fire Ms. Yovanovitch for privately expressing “disdain” for the Trump administration. Ms. Yovanovitch denied ever expressing that sentiment.