(Bloomberg) — An explosive leak from former National Security Advisor John Bolton’s unpublished book that says President Donald Trump wanted to freeze aid to Ukraine until its government investigated his political rival threatens to scramble the politics of the impeachment trial and bring new pressure on Republicans to call witnesses.Bolton’s account in the draft of his book, as described by the New York Times, fortifies the two central arguments made by Democrats in the trial: that Trump used the power of his office for political gain and that the senators urgently need to hear from witnesses the president blocked from testifying during the House inquiry.The disclosure comes as the president’s lawyers are preparing to deliver the meat of Trump’s defense when the trial reconvenes on Monday at 1 p.m. In an opening statement on Saturday, White House Counsel Pat Cipollone argued that House impeachment managers had failed to prove their case, in part, because they had no firsthand evidence in charging Trump with abuse of power. He said the real aim of Democrats was to overturn the 2016 election and interfere in November’s ballot.Bolton, who left the administration in September in disputes with Trump over policy, has that direct knowledge. He’s one of four current or former administration officials Democrats want to call as witnesses and has said he would testify if subpoenaed. His lawyer said previously that he has information that hasn’t been part of the public record.‘No Doubt’“There can be no doubt now that Mr. Bolton directly contradicts the heart of the president’s defense and therefore must be called as a witness at the impeachment trial of President Trump,” the seven House impeachment managers, led by Intelligence Chairman Adam Schiff, said in a joint statement Sunday night.Trump denied the allegations cited in Bolton’s draft in a tweet early Monday, adding that he released aid to Ukraine without any conditions.“I NEVER told John Bolton that the aid to Ukraine was tied to investigations into Democrats, including the Bidens. In fact, he never complained about this at the time of his very public termination. If John Bolton said this, it was only to sell a book,” he wrote.Bolton’s account challenges one of the “key facts” that Trump attorney Michael Purpura outlined on Saturday: that “not a single witness testified that the president himself said that there was any connection between any investigations and security assistance, a presidential meeting, or anything else.”Trump suggested another reason to prevent Bolton from testifying Monday, arguing that it was the job of the House to call Bolton during its impeachment proceeding even though witnesses have been called by the Senate in impeachment proceedings throughout history. “The Democrat controlled House never even asked John Bolton to testify,” Trump tweeted. “It is up to them, not up to the Senate!”It wasn’t immediately clear how much the Bolton revelations could change the dynamic on the question of trial witnesses. Four Republicans would have to defy Majority Leader Mitch McConnell to join with all Democrats to call witnesses at the trial, and Democratic leader Chuck Schumer on Friday described getting that outcome as a “hard road.”At least four GOP senators have expressed openness to hearing from witnesses, which could extend the trial by weeks, though they haven’t committed to a vote. Three GOP senators — Mitt Romney, Susan Collins and Lisa Murkowski — have said they’re considering voting to hear from new witnesses.No Republicans have yet said that Trump has committed an impeachable offense. With 67 votes required to convict, the president’s acquittal remains all but assured. Still, the more important audience for Bolton’s revelations will be the voting public who will decide in November whether Trump should be re-elected.The New York Times said Bolton has been circulating a draft of the manuscript to associates and it had been described to the Times by several people. Bolton also sent a draft to the White House as part of the standard review process for books by former administration officials.In the draft, according to the Times, Bolton wrote that in August the president told him he didn’t want to send $391 million in security assistance to Ukraine until the government there turned over material related to former Vice President Joe Biden, one of his potential Democratic challengers, and supporters of Trump’s 2016 opponent, Hillary Clinton.Other OfficialsBolton also wrote that several top cabinet officials had knowledge of Trump’s demands, including Secretary of State Michael Pompeo and Attorney General William Barr, as well as acting White House Chief of Staff Mick Mulvaney, according to the Times.Bolton’s lawyer, Charles Cooper, released a statement that doesn’t directly address the substance of the Times report. He said the manuscript was submitted to the National Security Council’s Records Management Division for standard prepublication security review for classified information on Dec. 30.Cooper said it was submitted with the “firm belief” that it contained no information that could reasonably be considered classified and that the “contents of Ambassador Bolton’s manuscript will not be reviewed or otherwise disclosed to any persons not regularly involved in that process.”“It is clear, regrettably, from The New York Times article published today that the prepublication review process has been corrupted and that information has been disclosed by persons other than those properly involved in reviewing the manuscript,” he said.At the heart of the Democrats’ impeachment case is the allegation that Trump took a sudden interest in Ukrainian corruption only after Biden entered the Democratic nomination race in April. They allege that over the ensuing months, Trump withheld military aid and a White House meeting sought by the recently elected Ukrainian President Volodymyr Zelenskiy, while seeking an investigation of Biden and his son Hunter Biden, who had served on the board of a Ukrainian energy company.President’s DefenseAttacking the foundations of the House arguments, Trump’s lawyers said there were good reasons for the president to not trust the assessments by U.S. intelligence agencies that Russia was acting alone in interfering in the 2016 election, and for his suspicions regarding corruption in Ukraine.They also said there was no pressure brought on Ukraine because the aid was released and Zelenskiy got a sought-after meeting with Trump with no investigation announced.Yet, over the course of their initial presentation, Trump’s legal team didn’t address several core allegations raised by Democrats as part of their argument that Trump abused his power.For example, the lawyers didn’t discuss Trump’s role in freezing aid to Ukraine, who else was involved in the decision and why it was done. The lawyers also didn’t address why the aid was finally lifted. And they didn’t provide any information or justification as to why Trump’s personal attorney, Rudy Giuliani, was leading an effort outside of normal diplomatic channels to pressure Ukraine to announce the investigations.The aid was released in early September and a meeting between Trump and Zelenskiy at the United Nations was arranged after an uproar over the revelation of an intelligence community whistle-blower’s complaint. The complaint raised alarms about Trump’s July phone call with Zelenskiy and a subsequent decision by White House lawyers to put the record of the conversation in a secure server to restrict access.As he left an event in Marshalltown, Iowa, Biden said he hadn’t seen the reports about Bolton’s book. “I don’t have any idea what’s in the book,” he said, “but if it in fact contradicts Trump, it’s not a surprise.”(Updates with Trump tweet in ninth paragraph.)–With assistance from Chris Strohm and Tyler Pager.To contact the reporters on this story: Billy House in Washington at bhouse5@bloomberg.net;Steven T. Dennis in Washington at sdennis17@bloomberg.net;Laura Litvan in Washington at llitvan@bloomberg.netTo contact the editors responsible for this story: Joe Sobczyk at jsobczyk@bloomberg.net, Kevin WhitelawFor more articles like this, please visit us at bloomberg.comSubscribe now to stay ahead with the most trusted business news source.©2020 Bloomberg L.P.