Two diplomatic figures named in the whistleblower complaint that’s at the heart of the impeachment inquiry against President Trump over his interactions with Ukraine’s president are slated to appear before Congress, The Daily Beast has learned. According to a senior Democratic aide, the State Department’s former special envoy for Ukraine—Kurt Volker—will appear before the House Foreign Affairs Committee on Thursday. Former Ambassador to Ukraine Marie Yovanovitch was previously scheduled to appear before the committee Wednesday, but will now appear on Oct. 11. The State Department inspector general has also asked for an “urgent” briefing with congressional committees tomorrow.

The whistleblower reportedly alleged that Volker was one of the officials attempting to “contain the damage” of the scandal by advising Ukrainians on how to handle the requests of Trump's personal attorney Rudy Giuliani—who has publicly admitted to pushing for corruption investigations into former Vice President Joe Biden and his son. The whistleblower also reportedly claimed Yovanovitch was recalled to Washington earlier than expected because of “pressure” from then-Ukrainian Prosecutor General Yuriy Lutsenko, who had spoken to Giuliani about the investigations and “collusion.”