“Everyone,” the ambassador, Gordon Sondland, said on Wednesday, “was in the loop.” Affirming that there was a quid pro quo, Mr. Sondland added that he had reluctantly worked with Rudy Giuliani, Mr. Trump’s personal lawyer, to pressure Ukraine to publicly commit to investigating Joe Biden “at the express direction of the president.”

Highlights: Here are key moments from Wednesday’s hearings, and five things we learned.

Response: Mr. Trump, reading from talking points scrawled in Sharpie, seized on one detail of Mr. Sondland’s testimony and said that he had wanted “no quid pro quo.”

Analysis: Democrats called Mr. Sondland their smoking gun, but Republicans think his testimony could help the president, our chief White House correspondent writes.

Scene: Certain days on Capitol Hill have an extra crackle. Yesterday was one of them, our correspondent writes.

What’s next: Two aides with firsthand knowledge of key events will testify today in the week’s final session. Here’s the latest.