(CNN) - Three-quarters of registered voters think witnesses should be allowed to testify in the Senate impeachment trial, which has reached a crucial inflection point, a new national poll from Quinnipiac University finds.

This includes 49% of Republicans who think witnesses should be allowed to testify, 75% of independents and 95% of Democrats.

President Donald Trump's legal team ended their opening arguments Tuesday afternoon and the trial now moves on to a 16-hour period for senators to ask questions. Following that could be a vote on whether to bring witnesses, which has long been seen as a critical vote but has taken on new importance in the wake of news reports on former Trump national security adviser John Bolton's book.

In his unpublished manuscript, Bolton writes Trump told him in August that he was withholding $391 million in aid until Ukraine announced a probe into the Bidens, according to The New York Times.