Many impeachment watchers have been eagerly anticipating the Wednesday testimony of Ambassador to the E.U. Gordon Sondland, because he had a direct line to Donald Trump, and his testimony is at odds with that of several other witnesses (he's already amended his testimony once).
But Tuesday afternoon's witness, former special envoy Kurt Volker, also has some key discrepancies to clear up and might be considered a warm-up to Sondland's appearance. Volker's main problem stems from the fact that he has asserted he was ignorant about the pressure campaign being applied to Ukraine.
The first sticking point concerns a July 10 meeting that Volker participated in during which Sondland announced to Ukrainian officials that they would have to initiate the investigations Trump wanted in order to get a White House meeting with Trump. In his testimony, Volker denied that "investigations" were ever discussed in that July 10 meeting. In fact, former national security adviser John Bolton shut down that meeting as soon as Sondland suggested that a White House meeting was conditioned on investigations.
Volker's ignorance of the extortion is also dubious given that he sent a text to a Ukrainian official just minutes before the July 25 phone call between Trump and Ukrainian President Volodymyr Zelensky in which he mentioned the 2016 investigation.
"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," Volker wrote to Zelensky aide Andrey Yermak.
So look to see how Volker attempts to thread these needles. He has been called as a witness for the Republicans.