He doesn't cut the profile of a member of "The Resistance," but Bolton's opposition to a pressure campaign to get Ukraine to investigate conspiracy theories may pit him against his former boss.
Ambassador William Taylor said U.S. aid to Ukraine was contingent on the country undertaking investigations that would help President Trump politically. Here are key parts of his written statement.
Former White House aide Fiona Hill told impeachment investigators on Monday that she and former Trump adviser John Bolton were troubled by actions by the president's private lawyer.
Fiona Hill, a British-born American foreign affairs expert, resigned as the president's top Russia analyst just days before the president's controversial call with his Ukrainian counterpart.