Former National Security Council official Tim Morrison testified Tuesday that EU Ambassador Gordon Sondland informed him on Sept. 7 that a hold on Ukraine military aid would be released if Ukraine announced investigations into Joe Biden and the 2016 election.

The big picture: Morrison, one of the impeachment witnesses called by Republicans, testified that he was told by then-national security adviser John Bolton to contact White House lawyers about Sondland's comments. Morrison said that Sondland represented himself as carrying out Trump's directive and that he understood the two investigations to be the same as those raised by Trump in his July 25 phone call with President Zelensky.

What to watch: Sondland himself has amended his closed-door deposition to say that he believed Ukraine military aid was conditioned on these investigations. He is expected to testify in a public hearing on Wednesday, where he will likely face questions about how he came to that understanding.

Go deeper: Live updates from Morrison and Kurt Volker's testimony