Top Ukraine Diplomat Testified Giuliani Spearheaded Pressure for Investigations

“I think the origin of the idea to get President Zelensky to say out loud he’s going to investigate Burisma and 2016 election, I think the originator, the person who came up with that, was Mr. Giuliani,” Mr. Taylor said, according to the transcript.

Democrats were not the only ones racing to position themselves for the inquiry’s new public phase.

A White House official said it would add two officials to help draft its public response to the inquiry. A senior administration official confirmed that Pam Bondi, the former Florida attorney general, and Tony Sayegh, a former aide to Treasury Secretary Steven Mnuchin, would join the staff on a temporary basis.

And Mr. Trump’s allies on Capitol Hill were considering changes to the Republican makeup of the Intelligence Committee and road-testing new lines of defense of Mr. Trump’s behavior.

The news of the public hearings came as House investigators were working this week to complete private depositions with a half-dozen or so remaining witnesses. On Wednesday, they questioned David Hale, the No. 3 official at the State Department, but three others skipped their scheduled appearances. Those officials were Russell T. Vought, the acting director of the Office of Management and Budget; T. Ulrich Brechbuhl, a counselor at the State Department who was among the officials listening in on Mr. Trump’s July 25 call with Mr. Zelensky; and Rick Perry, the energy secretary.

Two more high-profile witnesses — John R. Bolton, the president’s former national security adviser, and Mick Mulvaney, the acting White House chief of staff — are expected to defy congressional requests to appear on Thursday and Friday.

Democrats unexpectedly pulled a subpoena on Wednesday for Mr. Bolton’s deputy, Charles M. Kupperman, but it was not immediately clear why.

Mr. Kupperman had filed an unusual lawsuit last month asking a federal judge to determine whether he should listen to Mr. Trump — who ordered him to not cooperate with House investigators — or comply with the subpoena.