Watch: Kurt Volker and Tim Morrison testify in the third public impeachment hearing

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The third round of public impeachment hearings continue with former U.S. special envoy for Ukraine Kurt Volker and National Security Council official Tim Morrison testifying this afternoon.

The House impeachment investigation focuses on whether President Donald Trump abused his power by pressuring Ukraine President Volodymyr Zelenskiy to open investigations into his political rivals.

Volker, Energy Sec. Rick Perry and European Union ambassador Gordon Sondland, have been referred to as the "three amigos" in prior closed-door testimony and were charged with carrying out back-channel negotiations with the Ukrainian government.

Trump allegedly directed Volker and Sondland to work with Rudy Giuliani, his personal lawyer, to persuade Ukraine to investigate former Vice President Joe Biden and his son Hunter.

Volker, who resigned from the administration before delivering his private testimony, helped set up the July 25 call between Trump and Zelenskiy that is at the heart of the impeachment investigation. Volker said he was motivated to participate in the shadow foreign policy by a desire to improve U.S.-Ukrainian relations.

Morrison during his closed-door deposition last week said that he advised lawyers on the national security council that the phone call between Trump and Zelenskiy could be "damaging" if it got out. As a result, the call record was moved to a classified server.

Army Lieutenant Col. Alexander Vindman and Vice President Mike Pence aide Jennifer Williams testified in the morning. In his testimony, Vindman said Trump ignored prepared talking points on corruption from his national security staff.

The public impeachment hearings continue this week, with Sondland scheduled to testify on Wednesday morning, and Laura Cooper, the deputy assistant secretary of defense for Russia, Ukraine and Eurasia, expected to testify on Wednesday afternoon. David Hale, the undersecretary of state for political affairs, will give his testimony alongside Cooper.

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