(CNN) Former State Department senior adviser Michael McKinley testified Wednesday that he repeatedly asked Secretary of State Mike Pompeo for a show of support for the ousted US Ambassador to Ukraine Marie Yovanovitch — but was greeted with silence from the secretary of state, according to two sources with knowledge of his testimony.

That decision to not offer Yovanovitch support was a key reason McKinley decided to resign his job last week , the sources said.

McKinely testified Wednesday before the three committees leading the impeachment investigation into President Donald Trump, which are probing Trump's call with Ukrainian President Volodymyr Zelensky, as well as the President's personal lawyer Rudy Giuliani's efforts in campaign that included pushing for Yovanovitch's ouster.

In addition to the treatment of Yovanovitch, McKinley cited two additional reasons that drove his decision to leave, according to one of the sources. One was the transcript of the July 25 call between Trump and Zelensky — where Trump asked Zelensky to investigate the Bidens and badmouthed Yovanovitch — and the other was the unaddressed leadership issues documented in a damning State Department inspector general report released in August

Much of McKinley's testimony focused on internal dynamics at the State Department, which previous witnesses have told lawmakers were upended by Giuliani's efforts to go around normal channels in Ukraine to target Yovanovitch and push for Ukraine to open an investigation into Vice President Joe Biden and his son Hunter Biden.

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