National Security Council aide Alexander Vindman also to tell impeachment investigators Sondland made Ukraine meeting with Trump contingent on probes

A top official with the National Security Council plans to tell House impeachment investigators that he was concerned by President Trump’s July phone call with Ukrainian President Volodymyr Zelensky, saying that the president’s request to have the Ukrainians investigate Joe Biden and his son may have been interpreted as a “partisan play.”

Alexander Vindman, an Iraq war veteran who currently oversees Ukraine policy at the NSC, will be the first official with firsthand knowledge of the phone call at the heart of the impeachment inquiry to testify when he appears before House investigators on Tuesday.

According to a statement obtained by The Wall Street Journal, Mr. Vindman also plans to tell investigators that the U.S. ambassador to the European Union, Gordon Sondland, told a Ukrainian delegation in early July that the government in Kyiv needed to deliver specific investigations to secure a meeting with Mr. Trump. The statement says that the July 10 meeting was cut short by then-national security adviser John Bolton, which corroborates with what others have testified to.

Mr. Bolton didn’t respond to a request for comment.

Trump and Ukraine: A Guide to the Key Players

Mr. Trump sought to play down the testimony Tuesday morning, tweeting: “Why are people that I never even heard of testifying about the call.”

Mr. Trump added: “Just READ THE CALL TRANSCRIPT AND THE IMPEACHMENT HOAX IS OVER! Ukrain said NO PRESSURE.”