A high-ranking Army officer and top White House Ukraine expert is expected to tell House investigators Tuesday that he twice raised objections to his superiors about how President Trump Donald John TrumpFederal prosecutor speaks out, says Barr 'has brought shame' on Justice Dept. Former Pence aide: White House staffers discussed Trump refusing to leave office Progressive group buys domain name of Trump's No. 1 Supreme Court pick MORE and his administration were interacting with Ukraine out of a "sense of duty."

A draft of Lt. Col. Alexander Vindman's opening statement says he became worried when “outside influencers” were spreading a “false narrative” about Ukraine.

Vindman will testify behind closed doors Tuesday to the House Intelligence, Foreign Affairs, and Oversight and Reform committees. He will be the first official to testify who directly witnessed the July 25 phone call between Trump and Ukranian President Volodymyr Zelensky that is at the center of the House's impeachment inquiry.

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“I did not think it was proper to demand that a foreign government investigate a U.S. citizen, and I was worried about the implications for the U.S. government’s support of Ukraine,” Vindman says in his statement. “I realized that if Ukraine pursued an investigation into the Bidens and Burisma it would likely be interpreted as a partisan play which would undoubtedly result in Ukraine losing the bipartisan support it has thus far maintained.”