Transcript for John Bolton warns Americans that Trump poses danger to the republic
Now, to the new questions tonight, after Martha Raddatz's interview with president trump's former national security adviser John Bolton. She pressed him repeatedly, why didn't he share the information in his book with the American people during the president's impeachment trial? Here's Mary Bruce tonight. Reporter: President trump's longest serving national security adviser, John Bolton, is now warning Americans that trump poses a danger for the republic and should not be re-elected. We can get over one term. Two terms, I'm more troubled about. Reporter: In that explosive one-on-one with ABC's Martha Raddatz, Bolton says he heard first-hand from the president that he was withholding security aide to pressure Ukraine to investigate the Bidens. But Bolton refused to testify in the house impeachment proceedings. I think the way the house advocates of impeachment proceeded was badly wrong, I think it was impeachment malpractice. Reporter: You could have been that person providing that testimony. And it would not have made any difference. Reporter: You can certainly understand why your critics say, why didn't he come forward before? Why is he making a profit on this now? You know, it has -- it has nothing to do with making a profit. It has everything to do with making sure that the constitutional responsibilities that are accorded the different branches of government are carried out the right way. Reporter: Now, Bolton isn't ruling out that he could still testify and tonight, we know that top Democrats are seriously considering whether they should subpoena him. Democratic chairman Adam Schiff, who led the impeachment trial, saying that the public needs to know exactly what they have in this president. David? All right, Mary Bruce. Good to you have on a Monday night.
This transcript has been automatically generated and may not be 100% accurate.