Sen. Ron Johnson (R-WI) said Friday that in August, the U.S. ambassador to the European Union told the senator that military aid for Ukraine was linked To Trump’s push for Ukraine to investigate the origins of special counsel Robert Mueller’s probe, the Wall Street Journal reported.

Johnson spoke to the ambassador, Gordon Sondland, on Aug. 30, Johnson said.

The senator recalled to the Journal that Sondland told him that a deal would require Ukraine to appoint a prosecutor general to “get to the bottom of what happened in 2016—if President Trump has that confidence, then he’ll release the military spending.”

In a phone call the next day, Johnson said that he asked Trump about Sondland’s claims and that the President denied the arrangement.

“He said—expletive deleted—‘No way. I would never do that. Who told you that?’” the senator recalled.

Johnson told Trump that Sondland had told him about the supposed deal.

Though Sondland didn’t comment to the Journal, text messages of his were released Thursday after the former U.S. special envoy to Ukraine, Kurt Volker, turned them over to Congress.

In the texts, Volker and Sondland are seen discussing what appear to be several quid pro quos.

For example, the texts show that Volker and Sondland drafted a statement for Ukrainian President Volodymyr Zelensky to read, in which Zelensky would promise to “initiate and complete a transparent and unbiased investigation of all available facts and episodes, including those involving Burisma and the 2016 U.S. elections.”

In other text messages, including one exchange on Sept. 1 — the day after Johnson told Trump that Sondland had raised concerns about a quid pro quo — the acting ambassador to Ukraine, Bill Taylor, raised concerns with Volker and Sondland.

“Are we now saying that security assistance and WH meeting are conditioned on investigations?” he asked, to which Sondland responded, “Call me.”

The calls between Sondland and Johnson, and between Johnson and Trump, occurred several weeks after the administration became aware of an anonymous whistleblower complaint about Trump’s actions with regard to Ukraine.