Ambassador to the EU Gordon Sondland, slated to publicly testify in the impeachment inquiry on Wednesday, kept acting White House chief of staff Mick Mulvaney and Energy Secretary Rick Perry apprised of the Ukraine pressure campaign, according to emails obtained by the Wall Street Journal.

In one exchange, he assured the two that Ukraine President Volodymyr Zelensky was willing to talk about sham investigations into the Bidens and the 2016 election, just before a scheduled call with President Donald Trump.

“I talked to Zelensky just now. He is prepared to receive Potus’ call,” Sondland wrote. “Will assure him that he intends to run a fully transparent investigation and will ‘turn over every stone.'”

The emails come on the heels of an episode first revealed by top Ukraine diplomat Bill Taylor, who told the House Intel Committee that his aide overheard Trump urging Sondland to focus on the investigations. Taken together, new evidence paints a picture of Trump administration officials lashed ever closer to coercion — or as Democrats call it, bribery — of a foreign government for a domestic political advantage.

Sondland’s upcoming hearing is one of the most highly anticipated testimonies of the inquiry so far. Mulvaney and Perry have both resisted House subpoenas, with Mulvaney in particular asking a judge to decide whether or not he has to comply.