WASHINGTON — When John R. Bolton’s book manuscript landed on the desk of a White House national security aide shortly after Christmas, no one had to page through it to know that the draft could upend the impeachment proceedings against President Trump.

Now the question of who did review the book — and to what extent — has become a subject of the Senate impeachment trial of Mr. Trump. The White House has acknowledged that National Security Council staff members reviewed the draft, and that they briefed the White House counsel, Pat A. Cipollone.

But the president’s impeachment defense lawyers — Mr. Cipollone among them — insisted on Wednesday that they were unaware it contained the explosive revelation by Mr. Bolton, the former national security adviser, that Mr. Trump had directly linked aid for Ukraine to investigations he sought for personal gain.

“No one from inside the White House or outside the White House told us publication of the book would be problematic for the president,” Patrick F. Philbin, a deputy White House counsel and one of Mr. Trump’s lawyers, said on the Senate floor. “We assumed Mr. Bolton was disgruntled and wouldn’t be saying a lot of nice things about the president, but no one told us anything like that.”