Other witnesses — including Kurt Volker, the former U.S. envoy for the Ukraine peace talks, and David Hale, the top career diplomat at the State Department — also told House investigators that Pompeo had communicated with Giuliani.

Volker offered the caveat that Pompeo didn't always support the lawyer's dealings in Ukraine. He told House investigators he expressed concern to Pompeo about Giuliani's work involving Ukraine, specifically that he was spreading a false narrative about the country to Trump. Volker said Pompeo responded he was "glad" he was trying to correct the narrative.

Pompeo has distanced himself from Giuliani's dealings with Ukraine as he weighs his own broader political ambitions, including a run for Senate in Kansas. The White House has said it will not cooperate with the House impeachment inquiry.

During his testimony Wednesday, Sondland contradicted Trump's defense that there was no explicit exchange of U.S. assistance for Ukrainian political favors.

“Was there a ‘quid pro quo?’ Sondland said. “The answer is yes.”

“Everyone was in the loop. It was no secret," Sondland added. The ambassador also testified he communicated the quid pro quo to Ukrainian President Volodymyr Zelensky.