WASHINGTON — Ambassador Bill Taylor lit up President Trump’s impeachment inquiry Tuesday with what Democrats called the most detailed and damaging testimony yet.

Taylor, the acting ambassador to Ukraine, laid out in minute, day-to-day detail how he discovered the Trump administration’s efforts to strong-arm Ukraine into opening politically advantageous investigations by withholding key military aid in their conflict with Russia-backed separatists.

The testimony not only appears to confirm the central allegation against Trump in the impeachment inquiry — a quid pro quo — but also outlines the detailed steps top diplomats in Trump’s administration took to make that vision a reality.

EU Ambassador Gordon Sondland, who testified last week that Trump asked him to work with Trump’s private attorney Rudy Giuliani on Ukraine, appears especially involved as a shadow diplomat, ferrying Trump’s demands for an announcement on investigations into Democrat Joe Biden’s family and the 2016 U.S. election to Ukrainian President Volodymyr Zelensky.

And Trump, Taylor said, wanted Zelensky to announce the investigations himself.

Taylor's testimony appeared to mark a major moment in the Democrats' month-old impeachment investigation, which has moved at breakneck speed since September, when a whistleblower complaint about a phone call between Trump and Zelensky set alarm bells ringing.

Here are five key statements from Taylor’s opening remarks — and why they could be so damning for Trump and his administration.

“‘Everything’ was dependent on such an announcement”

Taylor said that Sondland told him on Sept. 8 that “everything” in U.S.-Ukrainian relations depended on Zelensky making “a public announcement of investigations,” and that Trump wanted to put Zelensky “in a public box” by making such a statement.

Taylor said Sondland expressed regret about previously tying only a White House visit to an investigation statement.

Sondland “told me that he now recognized that he had made a mistake” by tying the investigations merely to a White House visit, Taylor said. Sondland said “that Trump had told him that he wants President Zelenskyy to state publicly that Ukraine will investigate Burisma and alleged Ukrainian interference in the 2016 U.S. election.”

Those statements, if true, give crucial context as to why Trump was withholding badly needed military aid from Ukraine before his July 25 call with Zelensky: that he wanted investigations into both Vice President Joe Biden (his son Hunter served on Burisma’s board) and into an unfounded conspiracy theory that would somehow disprove the fact that Russia hacked Democrats in 2016.

That’s a helluva quid pro quo — and Trump’s attempts to put Zelensky “in a public box” by getting him to make a statement on-camera ordering the investigations showed he was looking for video fodder to buttress his own political agenda.

Taylor’s narrative is only bolstered by his reputation as a widely-respected career diplomat, who was tapped for the Ukraine post by Trump himself after serving for decades in both Republican and Democratic administrations.

“Security assistance money would not come until President Zelenskyy committed to pursue the Burisma investigation.”

Taylor said that on Sept. 1 another U.S. official, National Security Council member Tim Morrison, relayed that Sondland told a top Ukrainian official that “security assistance money would not come until President Zelenskyy committed to pursue the Burisma investigation,” which Taylor said “alarmed him” and was the first time he’d heard that security assistance for Ukraine and not just a White House meeting “was conditioned on the investigations” that Trump was demanding of his political rivals.

That information may be secondhand, but is particularly problematic — Taylor is saying that Trump was directly conditioning taxpayer-funded military aid to a critical U.S. ally in the middle of a defensive war against Russia on investigating Burisma, the company where former Vice President Joe Biden’s son Hunter worked. That might be corroborated sooner rather than later by others. Expect lawmakers to push Morrison on what exactly he heard Sondland say during his planned testimony to the committees next week.

Taylor said Trump wanted Ukrainian President Zelensky to “go to a microphone and say he is opening investigations of Biden and 2016 election interference.”

Taylor said Morrison relayed a conversation Sondland had with Trump where the president denied a “quid pro quo” — but “did insist that President Zelenskyy go to a microphone and say he is opening investigations of Biden and 2016 election interference, and that President Zelenskyy should want to do this himself.” Taylor quotes Sondland saying directly that Trump said Zelensky should “clear things up and do it in public.”

According to Taylor’s description, Sondland said Trump denied a “quid pro quo” in one breath and admitted in the next.

This sounds a lot like what Trump said himself to Zelensky on that now-infamous July 25 call — “do us a favor, though” and investigate the debunked theory that Ukraine has a server with the hacked emails from Hillary Clinton’s campaign and Democratic National Committee.

‘I will leave no stone unturned'

Taylor said Sondland recommended specific language for Zelensky to use when speaking to Trump about the investigations.

“Ambassador Sondland told me that he had recommended to President Zelensky that he use the phrase, ‘I will leave no stone unturned’ with regard to ‘investigations’ when President Zelensky spoke with President Trump,” Taylor said.

The language paints Sondland as a more-willing accomplice in the scheme to elicit investigations from Ukraine than Sondland’s own testimony from last week appeared to indicate.

Taylor said he then followed up with a phone call to one of Zelensky’s aides, who said Zelensky didn’t want to be used as a “pawn” in a U.S. re-election campaign. Taylor said he conveyed that concern to Volker and Sondland.

“‘investigations’ was a term”

Taylor said that he wasn’t given a read-out of the call in which Trump asked Zelensky to “look into” Biden and didn’t see them until they were released publicly — but by then, he already had a pretty clear idea of what Trump wanted.

“I had come to understand well before then that ‘investigations’ was a term that Ambassadors Volker and Sondland used to mean matters related to the 2016 election, and to investigations of Burisma and the Bidens,” Taylor said.

The fact that Taylor had such a strong and substantiated view that those two expressly political reasons were why Trump held up foreign aid lines up with what Trump himself seemed to be getting at in the call with Zelensky. Republicans have argued that Trump was just trying to root out corruption in the country. But it’s hard to square that claim with Taylor’s independent testimony, based on conversations he had outside of that call.