Impeachment investigators were expected to press Ms. Williams about what she thought about the July 25 call, as well as details about how much Mr. Pence knew about it and the extent of his understanding about the president’s attempts to pressure Ukraine to commit to investigations of his political rivals. Her testimony could draw Mr. Pence, who has defended the July 25 call, further into the inquiry. House Democrats subpoenaed Ms. Williams this morning after the White House attempted to keep her from testifying, according to an official working on the inquiry.
According to her LinkedIn profile, Ms. Williams has spent most of her adult life in government service, including 13 years at the State Department.
Two of the witnesses who previously testified, Lt. Col. Alexander S. Vindman, the top Ukraine expert on the National Security Council, and Christopher J. Anderson, a Ukraine specialist who worked at the White House, were also at the Capitol for a routine review of the testimony transcripts. Impeachment investigators have been releasing transcripts of witness testimony in recent days, and are expected to continue on Thursday.
House Republicans have until Saturday to request witnesses for the public impeachment hearings starting next week.
Democrats leading the impeachment inquiry officially invited Republicans on Thursday to request witnesses to appear in public hearings that will begin next week, but warned that witnesses must be directly relevant to the focus of the inquiry.
Representative Adam B. Schiff of California, the Democratic chairman of the House Intelligence Committee, said witnesses could be called to address whether the president used the power of his office to pressure a foreign government for his own political gain, or to address whether there were attempts to conceal or obstruct evidence of the president’s actions.
Mr. Schiff gave Republicans three days to provide a list of witnesses they would like to appear. Under a resolution passed by the House in October, Republicans have the right to request witnesses to appear in the public phase of the impeachment inquiry, but the decision is subject to a vote of the committee, which is controlled by Democrats.
The resolution was accompanied by a report by the House Rule Committee, which set out guidelines for the relevance of witnesses.