Donald Trump’s defenses tend to boil down to catchphrases: “no collusion,” for instance, or “no quid pro quo.” In the latter case, however, he may have hit a stumbling block. A new report suggests that Gordon Sondland, a U.S. ambassador whose text exchanges have been held up as defense that Trump did not pressure Ukrainian president Volodymyr Zelensky to open investigations into Joe Biden and his son, is expected to testify before House Democrats that he cannot personally exonerate Trump.

Per The Washington Post, Sondland will testify regarding a September 9 text exchange in which acting ambassador to Ukraine William B. Taylor remarked it was “crazy to withhold security assistance for help with a political campaign,” and Sondland responded, “I believe you are incorrect about President Trump’s intentions. The President has been crystal clear no quid pro quo’s of any kind.” Sources familiar with Sondland’s impending testimony say the ambassador will confirm that Trump dictated the response himself over a phone call with Sondland, as well that “It’s only true that the president said it, not that it was the truth.”

Sondland reportedly “believed Trump at the time and on that basis passed along assurances,” and is expected to testify that he was unaware of any efforts to investigate Hunter Biden over his ties to Ukrainian gas company Burisma. That said, Sondland had reportedly been working with Trump’s personal attorney, Rudy Giuliani, to secure the “deliverable” of Ukraine publicly vowing to investigate corruption, and mentioning Burisma by name. Incredibly, the source familiar with Sondland’s testimony added, “It was a quid pro quo, but not a corrupt one.”

Granted, it’s not all bad news for Trump—Sondland is expected to claim that Giuliani was largely responsible for souring efforts to make a closer ally of Ukraine, having “filled Trump’s head with a number of baseless conspiracy theories,” as well that Giuliani nudged the call with Zelensky closer to quid pro quo. “The statement that Rudy was demanding was a quid pro quo for a White House visit, there was no doubt about that,” the source familiar with Sondland’s testimony stated. “But it was about corruption, which from their perspective wasn’t particularly problematic, it’s an issue the U.S. had been dealing with there for years.”

Trump’s rationale for withholding $400 million in military aid to Ukraine will nonetheless be under intense scrutiny during Sondland’s testimony before three House committees on Thursday. The president has repeatedly suggested that Biden and his son be investigated regardless of the Ukraine call, even tweeting Sunday morning, “Where’s Hunter? He has totally disappeared! Now looks like he has raided and scammed even more countries! Media is AWOL.”

Last week, Sondland’s attorney stated, “Ambassador Sondland believes strongly that he acted at all times in the best interests of the United States, and he stands ready to answer the Committee’s questions fully and truthfully.”