Gordon Sondland, the U.S. ambassador to the E.U., will testify under subpoena Thursday as part of the Democrat-led impeachment campaign of President Donald Trump.

Sondland is expected to face questions over a Sept. 9 text message he sent another diplomat denying that Trump sought a quid pro quo from Ukraine in exchange for military aid.

Sondland reportedly will say Trump is who told him there was no quid pro quo. But the diplomat will also say he does not know whether or not Trump was being truthful.

Gordon Sondland, the U.S. ambassador to the European Union, will reportedly testify that President Donald Trump told him in a phone call in September that he did not want a quid pro quo from Ukraine involving military aid, but that he is not certain that the president was telling the truth.

A person familiar with Sondland’s planned testimony told The Washington Post that the diplomat will tell lawmakers of Trump’s quid pro quo denial that, “It’s only true that the president said it, not that it was the truth.”

Sondland is set to appear before Congress under subpoena Thursday as part of Democrats’ impeachment campaign against Trump. The diplomat is likely to be asked about his interactions with Trump, Trump lawyer Rudy Giuliani, and other diplomats regarding the administration’s posture toward Ukraine.

Sondland and Kurt Volker, the now-former envoy to Ukraine, met with Giuliani at Trump’s urging to negotiate with Ukrainian President Volodymyr Zelensky’s administration over investigations into whether Ukraine meddled in the 2016 U.S. election, as well as into whether Joe Biden pressured Ukraine’s president in 2016 to quash an investigation into Burisma Holdings, an energy company that had Hunter Biden as a board member. (RELATED: Diplomats’ Texts Show Trump Wanted To Leverage Ukraine’s President To Open Biden-Linked Investigation)

Giuliani is reportedly under criminal investigation over his links to Ukrainians who he worked with to push the theory about the Bidens. He has denied wrongdoing.

Sondland is likely to be asked about his remarks to another diplomat, Bill Taylor, and to Republican Wisconsin Sen. Ron Johnson regarding whether the investigations were part of a quid pro quo for military aid.

Johnson told The Wall Street Journal on Oct. 4 that Sondland told him during an Aug. 30 phone call Trump would release the military aid to Ukraine if Zelenksy announced the investigations.

The U.S. had mysteriously withheld hundreds of millions of dollars in military aid to Ukraine, Politico reported Aug. 28. Lawmakers did not know why the assistance had been withheld, with some wondering whether it was linked to Trump’s public calls for the politically charged investigations.

Johnson said Sondland told him if Zelensky appointed prosecutors to “get to the bottom of what happened in 2016 — if President Trump has that confidence, then he’ll release the military spending.”

“At that suggestion, I winced,” Johnson told TheWSJ. “My reaction was: Oh, God. I don’t want to see those two things combined.”

Johnson said Trump denied military aid was being withheld in exchange for the investigations.

“He said, [Expletive deleted] — No way. I would never do that. Who told you that?” Johnson said.

Taylor, who serves as charge d’affaires to Ukraine, also expressed concerns that Trump was using military aid as leverage against Zelensky.

“Are we now saying that security assistance and WH meetings are conditioned on investigations?” Taylor wrote to Sondland on Sept. 1, two days after the Politico report appeared.

“Call me,” Sondland replied.

Taylor raised the possibility of a quid pro quo again in a Sept. 9 text message to Sondland.

“As I said on the phone, I think it’s crazy to withhold security assistance for help with a political campaign,” he wrote.

Sondland replied five hours later, pushing back on Taylor’s assessment.

“Bill, I believe you are incorrect about President Trump’s intentions. The President has been crystal clear no quid pro quo’s [sic] of any kind. The President is trying to evaluate whether Ukraine is truly going to adopt the transparency and reforms that President Zelensky promised during his campaign,” he wrote.

Sondland will reportedly testify that he was merely relaying Trump’s denial to Taylor during the early morning text message, and that he does not know for certain whether Trump had a quid pro quo for military aid in mind in his dealings with Zelensky.

Sondland will also say Trump told him he did not want a quid pro quo, and “didn’t want anything from Ukraine,” according to the report.

But Sondland will also reportedly testify that a quid pro quo was in place over a face-to-face meeting with Zelesnky in exchange for opening the investigations.

“It was a quid pro quo, but not a corrupt one,” the source close to Sondland told The Post.

Text messages that Volker gave Congress before his testimony late in September indicate Trump wanted Zelesnky to announce opening of the investigations as a precondition to the Ukrainian leader visiting the White House.

“Most impt is for Zelensky to say that he will help investigation — and address any specific personnel issues — if there are any,” Volker wrote to Sondland on July 19, six days before Trump and Zelensky had a now-infamous phone call at the center of a CIA whistleblower complaint.

“Heard from White House — assuming President Z convinces trump he will investigate / ‘get to the bottom of what happened’ in 2016, we will nail down date for visit to Washington,” Volker wrote to a Zelensky aide shortly before the phone call.

Content created by The Daily Caller News Foundation is available without charge to any eligible news publisher that can provide a large audience. For licensing opportunities of our original content, please contact licensing@dailycallernewsfoundation.org.