John Bolton's book manuscript contains yet another revelation about the Ukraine affair that emerged just minutes before the Senate was to start debating whether to call impeachment witnesses – including Bolton himself.

This time, the new information puts Bolton in the thick of President Donald Trump's push for Ukraine to investigate the Bidens.

The bombshell dropped right before the Senate entered a new phase in Trump's impeachment trial with a debate over calling witnesses. Democratic Sen. Charles Schumer warned Republicans would 'rue the day' they failed to call witnesses, and impeachment manager Adam Schiff warned: 'The facts will come out. In all of their horror, they will come out.'

His impeachment lawyers have spent a week arguing the president did nothing wrong and nothing impeachable. According to the new information, reported in the New York Times, Trump told Bolton in early May of last year to help his campaign to pressure Ukraine to investigate the Bidens.

The drama came as Republican Sen. Lisa Murkowski of Alaska said she is a 'no' on calling witnesses, hours after Sen. Lamar Alexander of Tennessee said he would vote against calling them.

Democrats want to call former National Security Adviser John Bolton

That left just two Republicans saying they would vote for witnesses – Utah Sen. Mitt Romney and Maine Sen. Susan Collins.

Bolton, who has written a book that the White House National Security Council has told him not to publish for classification reasons, describes an Oval Office meeting where Trump gave the instruction. Also present was White House counsel Pat Cipollone – who has been leading Trump's defense.

Also there was Trump lawyer Rudy Giuliani and acting White House Chief of Staff Mick Mulvaney, Bolton writes. Mulvaney is the other senior figure Democrats have been demanding be called as a witness – after he was implicated in emails as potentially having knowledge of holding up military aide for investigations, which Mulvaney denies.

Democratic impeachment managers have relentlessly played a public statement Mulvaney made to White House reporters, when he acknowledged a quid pro quo and said it happens 'all the time' in foreign policy, only to walk back the statement.

According to the Times story on the manuscript, which Bolton has submitted to the National Security Counsel for classification review, Trump told Bolton to talk to the then-new Ukrainian president, Volodymyr Zelensky to get him to meet with the president's personal lawyer Rudy Giuliani.

Giuliani has been zealously heading a months-long investigation to dig up information on former Vice President Joe Biden and his son Hunter in Ukraine. Bolton says he never made the call Trump was seeking.

President Trump issued an immediate denial.

'I never instructed John Bolton to set up a meeting for Rudy Giuliani, one of the greatest corruption fighters in America and by far the greatest mayor in the history of N.Y.C., to meet with President Zelensky. That meeting never happened,' he said.

Sen. Susan Collins, R-Maine, walks past the Senate chamber prior to the start of the impeachment trial of President Donald Trump at the U.S. Capitol Friday Jan 31, 2020, in Washington

Giuliani told the Times Bolton was making up 'some' of the information, and stopped short of an outright denial while labeling him a 'scumbag.'

'I think he's making some of it up. He's sure making up — I wouldn't call it making it up, but he's acting like a real scumbag by never telling me that he objected once, and then saying I was a time bomb, or a firecracker or something,' he said.

'Let's put John Bolton under oath. Let's find out who's telling the Truth,' said House manager Rep. Adam Schiff in floor debate on witnesses Friday.

Trump made the request for an investigation into the Bidens in an infamous July 25 call that the president calls 'perfect.'

Giuliani is quoted int he initial Times story calling the account 'categorically untrue,' and he and Mulvaney and weren't around for Ukraine meetings.

Former White House Chief of Staff Gen. John Kelly, who served with Bolton, said at a speech in Florida this week that he believes Bolton.

The latest bombshell comes after a surprise statement by Sen. Lamar Alexander stating that he would vote against calling witnesses, in part because the case was already proven.

Murkowski issued a statement against witnesses citing the impeachment 'partisan.' She put it out minutes after the repot on Bolton's account that Trump directed him to push Ukraine on investigations.

'The House chose to send articles of impeachment that are rushed and flawed. I carefully considered the need for additional witnesses and documents, to cure the shortcomings of its process, but ultimately decided that I will vote against considering motions to subpoena,' Murkowski she said.

'Given the partisan nature of this impeachment from the very beginning and throughout, I have come to the conclusion that there will be no fair trial in the Senate. I don't believe the continuation of this process will change anything. It is sad for me to admit that, as an institution, the Congress has failed.'

Mikulski is close to Collins as part of a small group of Senate GOP centrists. With her and Alexander voting no, Collins – who is up for reelection in a purple state – is voting for witnesses.

The spotlight was back on Bolton after late-night disclosures about which senators might cross party lines on allowing witnesses. Democrats appeared short of assembling a majority to call Bolton an others to testify about what they know. Democrats have spent days saying the trial would be a sham and a cover-up without witnesses.

Bolton writes that Trump told him to contact Ukrainian President Volodymyr Zelensky to get him to meet with Giuliani

Giuliani has traveled to Ukraine in search of information about the Bidens

Former National security adviser John Bolton leaves his home in Bethesda, Md. Tuesday, Jan. 28, 2020

Bolton says White House counsel Pat Cipollone, who has been overseeing his impeachment defense, was present during the Oval Office meeting with Trump and Bolton

'I think he's making some of it up. He's sure making up — I wouldn't call it making it up, but he's acting like a real scumbag by never telling me that he objected once, and then saying I was a time bomb, or a firecracker or something,' said Giuliani

Sen. Lamar Alexander, R-Tenn., talks to reporters as he walks past the Senate chamber prior to the start of the impeachment trial of President Donald Trump at the U.S. Capitol Friday Jan 31, 2020. He is voting against calling witnesses

Who votes how will be the biggest drama in the final vote as Trump is certain to be acquitted in the Republican-controlled chamber.

And that decision is on track to happen late Friday after Republican Senator Lamar Alexander announced Thursday evening he would vote against calling additional witnesses, which likely doomed Democrats' efforts to call former National Security Adviser John Bolton to testify.

Even without the votes for witnesses, the senators were tasked with reaching some kind of a procedural agreement to move forward – possibly by sending lawmakers home for a few days.

Schumer said Friday afternoon there was no agreement. The process fight has high stakes: the Iowa caucuses are Monday, with three presidential candidates girding to get on the campaign trail. Sens. Elizabeth Warren and Bernie Sanders have big events scheduled in eastern Iowa Saturday, and Sen. Amy Klobuchar is climbing in the Iowa polls.

Trump is set to deliver his State of The Union speech Tuesday at prime time. He would be keen to declare himself acquitted, and Democrats would prefer to deny him the opportunity.

Schiff addressed the new Bolton revelations as he delivered a warning to senators poised to vote against witnesses.

'The witnesses the president is concealing will tell their stories,' he said. 'And we will be asked why we didn't want to consider that information when we had the chance.'

'The facts will come out. In all of their horror, the facts will come out,' he said. 'Witnesses will tell their stories in books and in the media.'