The reconstructed transcript of the July 25 call released by the White House did not include the word “Burisma.” But Lt. Col. Alexander S. Vindman, the top Ukraine expert on the National Security Council, also testified that when Mr. Zelensky is shown to have referred to “the company you mentioned,” he actually said “Burisma.” Colonel Vindman said his attempt to correct the record of the call to include the company’s name, and to reflect that Mr. Trump said that he had recordings of Mr. Biden, failed.

On Tuesday, Ms. Williams is scheduled to testify in public, becoming the latest in a series of diplomats to express their concerns about the call.

Over the weekend, Mr. Trump lashed out at Ms. Williams — “whoever that is,” he tweeted — saying that she should read the transcripts of the July 25 call and another one between the two leaders that took place in April. “Then she should meet with the other Never Trumpers, who I don’t know & mostly never even heard of, & work out a better presidential attack!” Mr. Trump wrote. A spokeswoman for Mr. Pence said merely, “Jennifer is a State Department employee.”

A White House official said some were not surprised by Mr. Trump’s attack on Ms. Williams, whom the official described as an innocent bystander in the impeachment mess, and expressed disappointment that senior staff on Mr. Pence’s team did nothing to defend her. The official spoke on condition of anonymity to offer a candid assessment. The person said it reflected poorly on the vice president that he was apparently unable to protect Ms. Williams from being publicly disparaged by the president.

Ms. Williams joined the Foreign Service in 2006 after spending a year as a political appointee working for Michael Chertoff, the secretary of homeland security, in George W. Bush’s administration. In addition to serving in Jamaica under Mr. Bush and in Beirut, Lebanon, under President Barack Obama, Ms. Williams spent about three years working for the State Department on the humanitarian crisis involving refugees in Syria. Six months before Mr. Trump became president, Ms. Williams was transferred to London to work as the deputy spokeswoman at the embassy there.