President Trump’s defense of his interactions with Ukraine hinges on the idea that he was fervently concerned about corruption in that country, so much so that he prioritized corruption investigations during his call with Ukrainian President Volodymyr Zelensky on July 25.

That argument is undermined by nearly all available evidence. Trump seldom talks about corruption as president — at least in the context of foreign countries — and never raised corruption during the Zelensky call. The investigations he requested then were predicated not on corruption but, instead, on pet theories promoted by his attorney Rudolph W. Giuliani: that something was fishy with a server in the 2016 campaign interference; and that former vice president Joe Biden had maybe done something untoward. In neither case is there evidence that the Trump-Giuliani concerns were warranted.

If Trump’s requests to Zelensky weren’t about corruption but, instead, about his own political gain, Trump is in trouble. It’s illegal to solicit aid from a foreign actor to benefit a campaign, which a Ukrainian probe into Biden in particular likely would be. Moreover, efforts to withhold a White House meeting until Zelensky launched new investigations — as E.U. Ambassador Gordon Sondland testified Wednesday had happened — or to withhold security assistance with the same aim might be an explicit use of presidential power for personal benefit.

In addition to directly alleging a quid pro quo that was well-known within the administration, Sondland’s testimony undercut Trump’s claims in another, quieter way. At several points in his testimony, he suggested it was only the announcement of investigations that was a priority for the White House.

House Intelligence Committee Chairman Adam B. Schiff (D-Calif.) asked Sondland at one point to clarify the outline of the quid pro quo.

“He had to get those two investigations if that official act was going to take place,” Schiff said.

“Correct,” Sondland replied. “He had to announce the investigations. He didn’t actually have to do them, as I understood it.”

Later, Daniel Goldman, counsel for the House Democrats, pressed Sondland on the point.

“You understood that in order to get that White House meeting that you wanted President Zelensky to have and that President Zelensky desperately wanted to have,” Goldman said, “that Ukraine would have to initiate these two investigations. Is that right?”

“Well, they would have to announce that they were going to do it,” Sondland replied.

“Right, because they — because Giuliani and President Trump didn’t actually care if they did them, right?” Goldman asked.

“I never heard, Mr. Goldman, anyone say that the investigations had to start or had to be completed,” Sondland said. “The only thing I heard from Mr. Giuliani or otherwise was that they had to be announced in some form. And that form kept changing.”

“Announced publicly?” Goldman asked.

“Announced publicly,” Sondland replied.

“And you, of course, recognized that there would be political benefits to a public announcement as opposed to a private confirmation, right?” Goldman asked.

“Well, the way it was expressed to me was that the Ukrainians had a long history of committing to things privately and then never following through,” Sondland replied. “So President Trump presumably — again, communicated through Mr. Giuliani — wanted the Ukrainians on record publicly that they were going to do these investigations. That’s the reason that was given to me.”

“But you never heard anyone say that they really wanted them to do the investigations,” Goldman said, “just that they wanted them to announce them.”

“I didn’t hear either way,” Sondland replied.

Goldman later pointed to testimony from acting Ukraine ambassador William B. Taylor Jr. in which he recalled Sondland saying that Ukraine needed to be in a “public box.”

“It goes back to my earlier comment that — again, coming from the Giuliani source, because we didn’t discuss this specifically, President Trump — that they wanted whatever commitments Ukraine made to be made publicly so that they would be on the record and be held more accountable,” Sondland said. “Whatever those commitments were."

It’s an interesting evolution in Sondland’s responses. It’s clear he understands the difference between an investigation that’s announced and one that’s completed. It also seems clear that he understands how the investigations might be politically useful.

On Sept. 9, for example, Taylor sent a message to Sondland saying, “I think it’s crazy to withhold security assistance for help with a political campaign.” Sondland, after speaking with Trump, replies that Taylor was “incorrect about President Trump’s intentions” but doesn’t question the link between the probes and politics.

What’s not clear is why Sondland introduced questions about the need for investigations to be completed. In the July 25 call with Zelensky, Trump didn’t request simply that investigations be announced but, instead, that they be conducted.

In early August, Sondland, working with Giuliani and then-Ukraine special envoy Kurt Volker, pushed to get such an announcement — in part to put Zelensky in a “box,” as Taylor testified. Sondland’s clarification about how an announcement would make investigations more likely seems like an understandable rationale for seeking an announcement, especially given how long it had taken to confirm the probes.

Under later questioning, Sondland said that Trump had told him he “just want[ed] Zelensky to do the right thing, to do what he ran on” — that is, address corruption. That came in early September, as questions about a stoppage in aid had become public and in response to Sondland’s questions about Taylor’s concerns.

So why introduce the loaded “he didn’t actually have to do them” qualifier?

One possibility is simply that it’s another manifestation of Sondland’s clear willingness to burn his bridges with the administration in his Wednesday testimony, that he’s throwing out a problematic scenario as a possibility. His explicit articulation that quid pro quo occurred is an apparent demonstration of that willingness to burn Trump.

Another possibility, of course, is that Sondland was under the impression that the investigations were in fact secondary to the announcement of the investigations. That’s a potentially significant development, strongly bolstering the idea that the intent of the investigations was purely political. The announcement itself would serve Trump in the way the late-October announcement of the reopening investigation into Hillary Clinton helped Trump in 2016. That reopening went nowhere, but the political damage had been done.

There were other, more significant components to Sondland’s testimony. But the significance of his suggestion that the call for investigation was simply a public relations move and nothing more shouldn’t be underestimated. If true, it severely undercuts Trump’s already shaky defense about what he wanted from Ukraine’s president.