President Donald Trump unleashed his sharpest attack yet on John Bolton after his former national security adviser depicted Trump as playing a central role in a politically motivated pressure campaign on Ukraine, as the U.S. Senate prepared on Wednesday to enter a new phase in the president's impeachment trial.
Senators were set to begin the first of two planned days of posing questions to both Trump's legal team and the Democrats in the House of Representatives lawmakers who have served as prosecutors in the trial on charges of abusing power and obstructing Congress arising from his request that Ukraine investigate political rival Joe Biden.
The questioning, set to begin at about 1 p.m. (1800 GMT), precedes a vote later in the week on whether to call witnesses including Bolton, as Democrats have sought.