Democrats have been pushing the Republican-led Senate to allow new witnesses, and others could include Mick Mulvaney, the acting White House chief of staff who played a key role in the Ukraine pressure campaign. A handful of Republican senators had indicated they would be open to hearing new witnesses, but by the end of last week, there were few signs that they would vote with Democrats on the matter.
“There can be no doubt now that Mr. Bolton directly contradicts the heart of the president’s defense,” Speaker Nancy Pelosi and Senator Chuck Schumer, the minority leader, said in a joint statement on Sunday after The New York Times’s article about Mr. Bolton’s account was published.
Mr. Bolton’s potentially explosive details about Mr. Trump’s motivations for freezing the military aid could provide the impetus that could potentially sway some Republican senators to reconsider hearing new testimony.
Mr. Bolton’s lawyer blamed the White House for the disclosure of the book’s contents, which Mr. Bolton submitted for a standard security review 12 days after the House impeached Mr. Trump. It is possible that the submission of Mr. Bolton’s book to the White House deepened desires to keep Mr. Bolton from testifying.
By Monday morning, some Republican senators had reached out to the White House, pressing for who had visibility into Mr. Bolton’s manuscript as the Senate trial unfolded a week earlier.
In his manuscript, Mr. Bolton describes an effort, along with Secretary of State Mike Pompeo and Defense Secretary Mark T. Esper, to push Mr. Trump to release the aid. Mr. Bolton said he also spoke with Attorney General William P. Barr about his concerns over the parallel diplomacy with Ukraine led by the president’s personal lawyer, Rudolph W. Giuliani. Mr. Barr, whom Mr. Trump mentioned in his July phone call with Mr. Zelensky, has tried to distance himself from Mr. Giuliani and the Ukraine matter.
Mr. Bolton, who has said he would testify at the Senate trial if he was subpoenaed, wrote in the manuscript that Mr. Pompeo told him privately that there was no basis to criticize the American ambassador to Ukraine at the time, Marie L. Yovanovitch. Career diplomats have testified that there was no justification to fire Ms. Yovanovitch. Mr. Giuliani and two of his associates had been pushing Mr. Trump to fire her since the spring of 2018.
Maggie Haberman contributed reporting.