WASHINGTON — Why Marie L. Yovanovitch, the ambassador to Ukraine, was recalled from her post two months early has become a central question in the Democratic-led impeachment inquiry into whether President Trump tried to pressure the country to investigate his political rivals. On Wednesday, David Hale, the State Department’s No. 3 official, will be pressed to provide answers.

Mr. Hale’s testimony before the House Intelligence Committee will be another weighty entry in his nearly four-decade career as a diplomat. As the under secretary of state for political affairs, Mr. Hale was among the department officials who grappled with how to handle the smear campaign led by Rudolph W. Giuliani, Mr. Trump’s personal lawyer, to oust Ms. Yovanovitch.

Ms. Yovanovitch and Philip T. Reeker, the acting assistant secretary in charge of European and Eurasian Affairs, told investigators that they asked Mr. Hale to talk to Secretary of State Mike Pompeo about issuing a statement in support of Ms. Yovanovitch. No such statement was ever made.

Mr. Hale testified behind closed doors this month that agency officials did not do so because they worried that it would “only fuel further negative reaction” and thought it would be better “to try to contain this and wait it out.”