Democrats have been pushing to have the Senate hear from Bolton, among other witnesses who did not provide testimony to the House during the impeachment inquiry. At the heart of the impeachment trial is Trump's July 25, 2019 call with Ukraine President Volodymyr Zelensky. Trump has denied the Democrats' claim that there was a quid pro quo and did so again following the Bolton report. Susan Collins, R-Maine, and Mitt Romney, R-Utah, have already indicated they will likely vote for Bolton, and potentially other witnesses. Because the GOP holds a 53-seat majority in the Senate, Democrats would need two more Republican members to vote to hear testimony from Bolton.

Source: Fox News January 27, 2020 14:36 UTC