The Bolton bombshell has rocked the Trump impeachment trial.

And while there’s no indication it will change the ultimate outcome, that has put Republicans on the defensive.

John Bolton is no Lev Parnas. He’s not some sketchy character under indictment. He’s a former acting U.N. ambassador, longtime hero to conservative hawks, and President Trump’s pick as national security adviser. What’s more, he’s a firsthand witness who had conversations about Ukraine with the boss (before he was ousted) and other top officials.

So when the New York Times reported on his soon-to-be-public manuscript, it quickly took center stage.

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Trump told Bolton in August “that he wanted to continue freezing $391 million in security assistance to Ukraine until officials there helped with investigations into Democrats including the Bidens,” says the Times account of the manuscript.

The president took to Twitter to deny the account shortly after midnight: “If John Bolton said this, it was only to sell a book.” And indeed, an Amazon pre-order page for the book, “The Room Where It Happened,” popped up yesterday.

The insta-controversy raises three major questions:

--Will four Republican senators vote to call Bolton as a witness?

Mitt Romney said the unpublished manuscript makes that increasingly likely, and Susan Collins said it strengthens the case, but they were already probable yes votes. Other GOP senators were saying yesterday that Bolton doesn’t matter, that it was a selective leak, that the facts of the case haven’t changed. Lindsey Graham said he wants to see the manuscript but that Trump’s side should be able to call witnesses if the Senate goes there.

But the manuscript does boost pressure on Republicans, especially those who are up for reelection and could face accusations of refusing to hear key evidence. If a half-dozen or more Republicans agree, there is safety in numbers. Nobody wants to cast the single decisive vote against Trump’s position.

--Who leaked the Bolton manuscript?

In a routine step, Bolton, a former Fox News contributor, submitted the book to the White House for pre-publication review of any classified information. The administration says no one outside the NSC got a copy. But the Times said “multiple people” described the manuscript.

Bolton’s lawyer, Chuck Cooper, says “it is clear, regrettably…that the pre-publication review process has been corrupted and that information has been disclosed by persons other than those properly involved in reviewing the manuscript.”

Why would any Trump official provide the information to the Times? The leaky White House once had officials who would damage the boss in service of their own agendas, but few if any remain. Maybe the administration wanted to get it out there and defuse it before the Senate trial ended.

Why would Bolton want such a leak? He’s been volunteering to testify, if subpoenaed, to no avail. Once the book was published, Bolton would have faced a firestorm for staying silent and allowing the Senate to acquit Trump without sharing his crucial evidence. He would have been assailed as greedy for holding his explosive allegations until his book was out. This leak, whether he was complicit or not, gets him off the hook.

Still, Bolton, Simon & Schuster and Javelin Literary issued a statement: “There was absolutely no coordination with the New York Times or anyone else regarding the appearance of information about his book.” The rest, they said, is “unfounded speculation.”

--How damaging is the Bolton book itself?

The reported manuscript contradicts several top officials. Bolton says Mike Pompeo privately acknowledged there was no basis for Rudy Giuliani’s claims that Ambassador Marie Yovanovitch was corrupt and the secretary of State believed Giuliani may have been acting on behalf of other clients.

Bolton also says he told William Barr about his concerns about Rudy after Trump’s July 25 call with Ukraine’s president, noting that Barr’s name was raised on the call. The attorney general has insisted he only learned about this in the middle of August.

And Mick Mulvaney was on at least one call between Trump and Giuliani, says Bolton, despite the chief of staff’s insistence he avoided such conversations to protect attorney-client privilege.

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As for the president, he is starting to turn on Bolton as a disgruntled ex-staffer who is lying to boost book sales. But this situation is different from his past attacks on Michael Cohen, Steve Bannon, Rex Tillerson, Jeff Sessions, Anthony Scaramucci, Omarosaand others who have broken with him. Bolton largely supports Trump’s foreign policy, even if he proved too hawkish for the president’s taste.

John Bolton’s account, whether it comes out in trial testimony or book form, will not be easy to dismiss.