Names likely to come up in the hearings include witnesses to, and participants in, the president’s scheme to withhold military aid to Ukraine until that country helped with his reelection:
■ Rudy Giuliani
The president’s personal lawyer. Acting in no official capacity other than serving as Trump’s personal lawyer, the former New York mayor met with several Ukrainian officials to pressure them into investigating the Biden family’s dealings in Ukraine in order to help the president’s 2020 reelection campaign.
■ Gordon Sondland
The US ambassador to the EU. GOP megadonor-turned-diplomat, Sondland was a hotelier from Oregon before joining the administration. He told Ukrainian officials that he believed the US aid was contingent on announcing investigations into the Bidens.
■ Mick Mulvaney
Acting White House chief of staff and director of Office of Management and Budget. A former Tea Party congressman from South Carolina, Mulvaney’s exact role in the Ukraine affair is unclear, and he has defied a House subpoena ordering him to testify. But according to witnesses, he was involved with the hold placed on military aid to Ukraine.
■ Kurt Volker
Former US special representative to Ukraine. Volker worked with Ukrainian officials to craft a statement on investigations that would satisfy the president enough to release the nearly $400 million aid. He resigned just before agreeing to testify, and then supplied Congress with text messages hinting at the link between aid and a Biden investigation.
■ William ‘Bill’ Taylor
US chief envoy to Ukraine — testifies Wednesday. Still serving as charge d’affaires in Kyiv, Taylor ignored instructions to stay quiet, flew back to Washington, and testified that his “clear understanding” was that the administration was demanding a quid pro quo from Ukraine’s president: “security assistance money would not come until the President [of Ukraine] committed to pursue the investigation.”
■ George Kent
Deputy assistant secretary of state for European and Eurasian Affairs — testifies Wednesday. A bow-tied Foggy Bottom veteran, Kent defied orders from the administration to tell lawmakers that Giuiliani inserted himself into Ukraine policy and led a “campaign of lies” to oust Ambassador Marie Yovanovitch.
■ Marie Yovanovitch
US former ambassador to Ukraine — testifies Friday. A highly regarded career diplomat, Yovanovitch was abruptly removed as envoy to Ukraine after Giuliani orchestrated a whispering campaign accusing her of disloyalty to the president.
■ Fiona Hill
Former senior official for Russia and Europe on the National Security Council (NSC). Hill left her position at the NSC just as the pressure campaign against Ukraine was heating up, but was in office long enough to witness Sondland telling Ukrainian officials they needed to open investigations to secure an Oval Office meeting with Trump.
■ Lt. Col. Alexander S. Vindman
National Security Council, director for European affairs. Vindman listened in on the July 25 phone call. He has been a US military officer and diplomat for more than two decades. He served in Iraq, was injured in an IED attack, and received a Purple Heart. In testimony, he told House members that the transcript of the phone call released by the White House was missing references to Biden.
■ John Bolton
Former national security adviser. Longtime GOP foreign policy hand with a hawkish outlook. Bolton abruptly resigned in September. He has not agreed to appear before Congress but was said to be outraged by the efforts to pressure Ukraine.
■ Jennifer Williams
Special advisor to Vice President Pence on European and Russian affairs. Williams listened in on the July 25 phone call that triggered the whistle-blower’s complaint. She testified behind closed doors last week.
■ Mike Pompeo
Secretary of State. Pompeo was on the July 25 phone call. He has denied any wrongdoing and defied a subpoena for documents. He has been Secretary of State since April of 2018.
■ Laura Cooper
Deputy assistant secretary of defense for Russia, Ukraine, and Eurasia. Cooper oversees Ukraine policy, including the military aid that had been frozen by the Trump administration. She voluntarily appeared before Congress.
Although the allegations in the initial whistle-blower complaint have now been corroborated, Republicans continue to insist that he or she must come forward publicly. Republicans may try to use the hearings to unmask the tipster, which Democrats fear would send a chilling message to other potential whistle-blowers.