“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. But he also conceded that he had never spoken directly with Mr. Trump — a fact Republicans intend to highlight in next week’s hearing.
Democrats were not the only ones racing to position themselves for the inquiry’s new public phase.
A senior administration official said it would add two officials to help draft its public response to the inquiry. The 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.
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; and Rick Perry, the energy secretary.
Still, they continued to pursue administration officials who could help round out their narrative of what transpired. On Wednesday evening, a lawyer for Jennifer Williams, a national security aide to Vice President Mike Pence who listened to a July phone call in which Mr. Trump pressed Mr. Zelensky for the investigations, released a cryptic statement indicating she might testify as scheduled on Thursday.
“Jennifer is a longtime dedicated State Department employee,” said the lawyer, Justin Shur. “If required to appear, she will answer the committees’ questions. We expect her testimony will largely reflect what is already in the public record.”
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.