Lt. Col. Alexander Vindman is a name that might not be familiar to you, and if not for the ongoing impeachment inquiry in the House, we may never have known him. Vindman was the first current White House official to give a deposition, and was one of the first witnesses to provide direct, firsthand confirmation of numerous details in an anonymous whistleblower's complaint that first fueled the inquiry.
Testifying in the House impeachment inquiry, Kurt Volker said he believes now, thanks to hindsight and the testimony of other witnesses, that Trump was using the aid to compel Ukraine to investigate Biden and his son Hunter, who was on the board of a Ukrainian gas company, Burisma.
Separately, House general counsel Douglas Letter told a federal appeals court in Washington that lawmakers were examining the truthfulness of the written answers the president provided in former Special Counsel Robert Mueller's investigation of Russian interference in the 2016 presidential election.
House Intelligence Chairman Adam Schiff and Republican California Rep. Devin Nunes will lead the sessions.
Volker and former National Security Council Russia expert Tim Morrison are scheduled to appear on Tuesday afternoon. She argued members of Congress are filling their constitutional duty by conducting an impeachment inquiry after evidence of a possible wrongdoing by the president surfaced.
Volker, the former USA special envoy to Ukraine, resigned from his post one day after the release of a whistleblower report alleging a coverup by the White House of a call between Trump and Ukraine's President.
The US Senate majority leader Mcconnell says "it's inconceivable" senate will have 67 votes to remove Trump from office. Morrison will testify alongside Volker, who was also involved in White House meetings.
President Donald Trump's seemingly impromptu weekend visit to Walter Reed National Military Medical Center sparked public concern, which his physician attempted to allay by releasing a statement, Monday.
The Democratic-led House impeachment inquiry is examining whether Trump sought to leverage Zelensky's desire for an Oval Office meeting and almost $400-million in frozen USA security aid that Ukrainian forces needed to battle Russia-backed separatists in return for gaining political advantage over Biden.
Mr Morrison said Mr Sondland and Mr Trump had spoken approximately five times between July 15 and September 11 - the weeks that $391 million in United States assistance was withheld from Ukraine before it was released.
Vindman was testifying that he spoke to two people about providing a read out of the July 25 call. "Ambassador Sondland replied that 'He's going to do it, ' adding that President Zelensky will, quote, 'do anything you ask him to'".
Trump is the fourth US president to face an impeachment inquiry.