The House impeachment hearings hit a critical moment on Wednesday with the appearance of perhaps the most significant witness on the public schedule. Gordon D. Sondland, the Trump donor now serving as ambassador to the European Union, will be asked about his role in pressuring Ukraine to open investigations into Democrats and any link to American security aid.
The basics: Who, what, when and how to watch.
Who: Mr. Sondland will appear by himself in the morning session. Laura K. Cooper, a deputy assistant defense secretary, and David Hale, the under secretary of state for political affairs, will testify together in the afternoon session.
What: The House Intelligence Committee, led by its chairman, Representative Adam B. Schiff, Democrat of California, will continue to examine the case for impeaching President Trump. The Republican minority, led by Representative Devin Nunes of California, will again work to poke holes in testimony implicating the president.
When and Where: The morning proceedings start at 9 a.m. Eastern in the vaulted, columned chambers of the House Ways and Means Committee, and could last until the early afternoon. The second set of hearings is scheduled to start around 2:30 p.m., depending on when the morning session is finished.
How to Watch: The New York Times will stream the testimony live, and a team of reporters in Washington will provide real-time context and analysis of the events on Capitol Hill. Follow along at nytimes.com, starting a few minutes before 9.
The president’s main agent on Ukraine inside government will be forced to explain inconsistencies in his account.
Mr. Sondland, who told other presidential advisers that Mr. Trump had put him in charge of Ukraine policy, faces a challenging morning as lawmakers will grill him about conflicts between his previous closed-door testimony and versions of events offered by other witnesses.
Mr. Sondland has already been compelled to amend his testimony once by saying that he now recalled telling a senior Ukrainian official that the release of frozen American security aid probably depended on a public commitment to investigate Democrats, a revision he made only after another Trump administration official told investigators about the conversation.
A favor, a phone call and an aid freeze: Sondland will be asked to explain Trump’s role in the pressure campaign.
While Republicans derided many previous witnesses for offering only secondhand accounts, Mr. Sondland was in direct contact with Mr. Trump and will be asked about the president’s instructions to him. Along with Rudolph W. Giuliani, the president’s personal lawyer, Mr. Sondland was at the center of the effort to press Ukraine to turn up damaging information about Democrats.
He will be asked in particular about a telephone conversation he had with Mr. Trump on July 26, the day after the president pressed President Volodymyr Zelensky of Ukraine to “do us a favor” by investigating Democrats. Mr. Sondland was on the outdoor patio of a restaurant in Kyiv, the Ukrainian capital, and the president spoke loudly enough that the ambassador held the phone away from his ear, allowing others at the table to hear, including an embassy official who told House investigators about it last Friday.
As Republicans seek to protect Mr. Trump, they may portray Mr. Sondland as acting on his own to link the security aid to the investigations without explicit direction from the president.
Ms. Cooper has said that there was a consensus within the government that Ukraine was making progress on corruption when the White House abruptly froze the security aid without explanation for a review. Mr. Hale has described pushing unsuccessfully for the State Department to defend Marie L. Yovanovitch, the ambassador to Ukraine who was targeted by Mr. Giuliani and ultimately removed from her post.
Before then, catch up on some important background on the impeachment inquiry.
The three witnesses have already appeared for closed-door depositions in the inquiry. Read transcripts or key excerpts from their testimony here: Mr. Sondland, Ms. Cooper, Mr. Hale.
Mr. Trump repeatedly pressured Mr. Zelensky to investigate people and issues of political concern to Mr. Trump, including the former vice president. Here’s a timeline of events since January.
A C.I.A. officer who was once detailed to the White House filed a whistle-blower complaint on Mr. Trump’s interactions with Mr. Zelensky. Read the complaint.