On Capitol Hill, four witnesses are slated to testify today as part of the televised impeachment hearings into whether President Trump withheld military aid from Ukraine to pressure the Ukrainian president to investigate Trump’s political rival Joe Biden and his son. This morning, congressional lawmakers will hear testimony from Lt. Col. Alexander Vindman, the top Ukraine expert for the National Security Council, and Jennifer Williams, a special adviser to Vice President Mike Pence and a member of his National Security Council staff.

Both Vindman and Williams listened in on the July 25 phone call between President Trump and Ukrainian President Volodymyr Zelensky, which is at the center of the impeachment inquiry. In earlier closed-door testimony, Vindman said the White House transcript of the July 25 phone call omitted key words and phrases, including an explicit mention of Burisma Holdings by the Ukrainian president. Trump was trying to pressure the Ukrainian president to publicly announce an investigation into Joe Biden’s son Hunter and his role on Burisma’s board. Vindman also testified that his attempts to include the omissions in the transcript failed. In her previous testimony, Jennifer Williams called the July 25 phone call between Trump and the Ukrainian president “unusual and inappropriate.”

This afternoon, the two witnesses to testify will be former U.S. special envoy to Ukraine Kurt Volker and former National Security Council official Timothy Morrison. In a now-released text message, Volker wrote to one of President Zelensky’s aides only hours before the July 25 phone call, writing, “Heard from White House — assuming President Z convinces trump he will investigate / ‘get to the bottom of what happened’ in 2016, we will nail down date for visit to Washington.” Timothy Morrison had been the top Russia staffer on the National Security Council until he resigned last month ahead of his closed-door testimony in the impeachment hearings. Morrison also listened in on the July 25 phone call and later said he thought it could be damaging to U.S.-Ukrainian relations. He’s also said he was surprised to learn that the call’s transcript was put on a top-secret server, which many say was part of a White House cover-up.

These four testimonies today come after House Democrats released the transcript of the closed-door testimony of David Holmes, a senior political officer at the U.S. Embassy in Kiev. He told lawmakers Ukrainian officials “came to understand what was required” to access U.S. military aid and a meeting with President Trump. Holmes is slated to testify Thursday. On Monday, President Trump said he was strongly considering providing a written testimony as part of the ongoing impeachment inquiry. Democracy Now! will be live-streaming the impeachment hearings in full at democracynow.org.