Transcript for Trump's team gears up for rebuttal in Senate impeachment trial
coming up. We do turn to Washington and that bombshell report. "The New York Times" reporting on the draft of national security adviser John Bolton's book, and he claims president trump told him aid to Ukraine would be held. Jon Karl is tracking this breaking news. Reporter: President trump's former national security adviser John Bolton is the witness Democrats want to testify in the senate trial more than any other. The report overnight in "The new York Times" shows just how key he may be to the case against the president. Four weeks ago, Bolton submitted the manuscript to the white house for a standard review to make sure it doesn't contain classified information. Bolton writes, president trump told him in August he wanted to continue withholding military aid to Ukraine until officials there launched investigations into trump's rivals, including Joe Biden. This firsthand account directly contradicts what the president's lawyers argued in defending him in the senate trial just this weekend. There is simply no evidence anywhere that president trump ever linked security assistance to any investigations. Reporter: President trump denied the claims overnight tweeting, quote, I never told John Bolton that the aid to Ukraine was tied to investigations into Democrats. Thanks to Jon for that. We'll have live coverage of the senate trial starting at 1:00 eastern right here on ABC.
This transcript has been automatically generated and may not be 100% accurate.