Jennifer Williams, an aide to Vice President Mike Pence, and National Security Council aide Lt. Col. Alexander Vindman stand before the House Intelligence Committee on Capitol Hill. Picture: AP Photo/Andrew Harnik

Washington – Senior U.S. officials told impeachment investigators in Congress on Tuesday they were concerned by President Donald Trump’s effort to get Ukraine to investigate a political rival, with one White House official calling it a “shock.”

The third day of impeachment hearings conducted by the House of Representatives Intelligence Committee marked the first time that officials from inside the White House publicly expressed their misgivings about a freewheeling pressure campaign that now threatens Trump’s presidency.

The White House’s top Ukraine expert, wearing his Army dress uniform, said Trump had made an “improper” demand of Ukraine President Volodymyr Zelenskiy in a July 25 phone call that has become the centerpiece of the Democratic-led impeachment probe of the Republican president.

“Frankly, I couldn’t believe what I was hearing. It was probably an element of shock that maybe, in certain regards, my worst fear of how our Ukrainian policy could play out was playing out,” Army Lieutenant Colonel Alex Vindman said.

As he was testifying, the White House’s official Twitter account attacked his judgment – undermining the same man the administration appointed to lead its European affairs brief at the National Security Council.