House Intelligence Committee Chairman Adam Schiff Adam Bennett SchiffSchiff to subpoena top DHS official, alleges whistleblower deposition is being stonewalled Schiff claims DHS is blocking whistleblower's access to records before testimony GOP lawmakers distance themselves from Trump comments on transfer of power MORE (D-Calif.) said the committee expected to hear on Tuesday from key witnesses such as Lt. Col. Alexander Vindman Alexander VindmanImpeachment witness Alexander Vindman calls Trump Putin's 'useful idiot' The Hill's Morning Report - Sponsored by The Air Line Pilots Association - Trump, Biden renew push for Latino support Strzok: Trump behaving like an authoritarian MORE, a top Ukraine expert on the National Security Council (NSC), and Jennifer Williams, an aide to Vice President Pence. The panel also plans to hear from Kurt Volker Kurt VolkerGOP senators request details on Hunter Biden's travel for probe Yovanovitch retires from State Department: reports Live coverage: Senators enter second day of questions in impeachment trial MORE, former special envoy to Ukraine, and Tim Morrison, a top NSC official.

Schiff said on Wednesday that lawmakers plan to hear from U.S. Ambassador to the European Union Gordon Sondland, who revised his testimony to say he believed the president "likely" conditioned nearly $400 million in aid to opening such probes. Later that afternoon, they will hear from top Defense official Laura Cooper, who testified about decisions to withhold the aid, and David Hale, the Under Secretary of State for Political Affairs.

Democrats will wrap up the second week of public hearings with testimony from Fiona Hill, former NSC senior director for Europe and Russia, who testified about her concern that Trump's lawyer Rudy Giuliani Rudy GiulianiThe Hill's Campaign Report: GOP set to ask SCOTUS to limit mail-in voting CIA found Putin 'probably directing' campaign against Biden: report Democrats fear Russia interference could spoil bid to retake Senate MORE and others sought to remove a top diplomat to Ukraine.

The announcement comes one day before Democrats are expected to hold their first public hearing, in which they hope two career State Department officials will deliver convincing testimony about Trump pressing Ukrainian President Volodymyr Zelensky to open investigations into interference in the 2016 election and former Vice President Joe Biden Joe BidenFormer Pence aide: White House staffers discussed Trump refusing to leave office Progressive group buys domain name of Trump's No. 1 Supreme Court pick Bloomberg rolls out M ad buy to boost Biden in Florida MORE and his son.