Former National Security Council aide Tim Morrison says one of his colleagues warned him about President Donald Trump’s European Union ambassador, Gordon Sondland, and even coined a name for her concerns: “the Gordon problem.”

Morrison is testifying Tuesday in House Democrats’ impeachment inquiry.

Other witnesses have testified that Sondland talked directly to Trump as the president pushed Ukraine to investigate Democrats. Sondland, who testifies Wednesday, tried to negotiate with the Ukrainians for the investigations.

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Sondland also clashed with some in the White House as he took a leading role in Ukraine policy, including former adviser Fiona Hill, who Morrison said coined the phrase.

After talking to Hill, Morrison said he kept track of what Sondland was doing and “didn’t necessarily always act” on what he suggested.