In an exclusive interview with ABC News, Bolton offered a brutal indictment of his former boss, saying, "I hope (history) will remember him as a one-term president who didn't plunge the country irretrievably into a downward spiral we can't recall from. We can get over one term -- I have absolute confidence, even if it's not the miracle of a conservative Republican being elected in November. Two terms, I'm more troubled about."
In the interview with ABC News Chief Global Affairs Correspondent Martha Raddatz and in his new book, "The Room Where It Happened," Bolton paints Trump as "stunningly uninformed," making "erratic" and "irrational" decisions, unable to separate his personal and political interests from the country's, and marked and manipulated by foreign adversaries.
"I don't think he's a conservative Republican. I'm not going to vote for him in November -- certainly not going to vote for Joe Biden either. I'm going to figure out a conservative Republican to vote in," he told Raddatz.
What Bolton says to critics
Since excerpts of the book -- out June 23 -- leaked, Bolton has faced a tsunami of criticism both from Trump and his allies, for betraying his trust, and from Trump's critics, for coming out against the president now when he refused to testify before the House impeachment hearings and stayed silent with Trump on trial in the Senate.
Trump himself has blasted Bolton as a "wacko" and "liar," while accusing him of revealing classified information and attacking him personally: "Everybody in the White House hated John Bolton." Those comments contradict what Trump said just months ago after Bolton left the administration, telling reporters in November, "I like John Bolton. I always got along with him."
In his interview, Bolton predicted Trump's response would be "volcanic," countering, "It's typical of the Trump administration that when faced with criticism, they don't deal with the substance of the criticism, they attack the person, which I fully expect and doesn't surprise me."
"The president isn't worried about foreign governments reading this book. He's worried about the American people reading this book," Bolton added, saying he was "very conscious" to avoid including classified information, but, "The people of the country need to hear the reality."
A federal judge ruled Saturday that while Bolton's book can be released, publishing it without formal clearance from the White House "has exposed his country to harm and himself to civil (and potentially criminal) liability."
Pressed by Raddatz on his own support for Trump, Bolton called it a "mistake."
"I overrated the chances to make this into a coherent, rational, systematic, decision-making process, to advance American interests. ... That turned out not to be right," he said, adding that he stayed for 17 months "because the stakes are so high that I thought I could continue to make a contribution."
Why Bolton didn't speak out sooner
The critics have not been swayed by Bolton's explanation for why he stayed silent for months, until his book was ready for release. Last fall after resigning -- Trump said he was fired -- he rejected a request to testify before the House and said he would testify only if a judge ordered him to obey a subpoena. The House declined to issue the subpoena to avoid a legal battle. Bolton later said he would obey a subpoena if one was issued by the Senate, but the Republican-controlled Senate did not issue one.
Bolton now said his testimony wouldn't have mattered, while also accusing House Democrats of "impeachment malpractice" for not taking their time and widening their inquiry's scope to include potentially impeachable offenses that Bolton only alleges publicly for the first time in his book.
"I didn't think the Democrats had the wit or the political understanding or the reach to change what, for them, was an exercise in arousing their own base, so that they could say, 'We impeached Donald Trump,'" he said, adding "that conduct (is) almost as bad and somewhat equivalent to Trump."
Bolton told Raddatz he now has "an obligation to let the American people know what it's like in the White House and what their leader is doing."
But pressed about what public obligation he had at the time, he again turned to how the probe was initially conducted.
"It's not my obligation to help the Democrats out of their own problem. My judgment was that I was prepared to testify. But I think now this is actually a better time to tell the story because now the American people can look at it in the context of the most important political decision we make as a nation every four years," he said.
The Republican-controlled Senate ultimately voted not to call any witnesses to testify in Trump's trial, but Bolton now argues it wouldn't have made a difference.
"Minds were made up on Capitol Hill, and my feeling was in the midst of all the chaos that had been created, this would have come and gone, and nobody would have paid any attention to it," he said.
What Bolton witnessed on Ukraine
While congressional Republicans have had a muted response to Bolton's allegations, his account might have moved the needle. Bolton is the first witness to come forward alleging that Trump directly told him that he was tying Ukrainian investigations into his political rival, former Vice President Joe Biden, to his hold on nearly $400 million of U.S. security assistance to Ukraine, which is battling Russian-led separatists in its eastern provinces.
In fact, Bolton's claims countered many of the legal defenses put forward by Trump's lawyers and Republicans, including that Trump never connected the investigations and the assistance, that Trump instead cared about combating corruption in the country and that the Ukrainians never knew about the connection.
"The defense of the president was, he cares about the general corruption in the Ukraine, and that was on his mind -- that's utter nonsense," Bolton told ABC News, adding the Ukrainian government "fully understood" the connection.
"He was bargaining to get the investigation, using the resources of the federal government, which I found very disturbing," Bolton said.
He heard it from Trump himself on Aug. 20, he claimed, when Trump "directly linked the provision of that assistance with the investigation."
Trump has denied that, tweeting in January, "I NEVER told John Bolton that the aid to Ukraine was tied to investigations into Democrats, including the Bidens."
Bolton said Trump is lying, "and it's not the first time either."
According to Bolton, that connection was "widely understood at senior levels in the government," too, including the White House, State Department, Pentagon and Department of Justice.
Specifically, Secretary of State Mike Pompeo, Defense Secretary Mark Esper, and Attorney General Bill Barr were all aware and equally "alarmed" as he, according to Bolton, who also said he had conversations about the legality of it with the White House counsel's office and Barr -- something Barr's spokesperson has denied.
Bolton said they all were actively working to convince Trump to separate the aid from any Ukrainian probe.
"People in the aftermath, in light of the impeachment investigation thought that those of us like Pompeo and Esper and myself should have been sort of junior woodchuck FBI agents looking for evidence of impeachable offenses. What we were all trying to do was get the assistance released to the Ukraine because it was in America's interests to do so."
What Bolton calls a troubling pattern
"When it comes to reelection, his attention span was infinite, and his focus was very direct. It's just too bad there wasn't more of that when it came to national security," Bolton told ABC News.
He cited specific examples of strongmen leaders who had "mastered the art of ringing (Trump's) bells," including Xi Jinping of China, Vladimir Putin of Russia, and Recep Tayyip Erdogan of Turkey.
According to Bolton, Erdogan asked Trump to intervene on behalf of Halkbank, a Turkish state-run bank that faced possible criminal charges for violating U.S. sanctions against Iran and was said to operate like a slush fund for Erdogan's family.
"And the president said to Erdogan at one point, 'Look, those prosecutors in New York are Obama people. Wait till I get my people in and then we'll take care of this,'" Bolton said.
"I've never heard any president say anything like that. Ever," Bolton added. "It did feel like obstruction of justice to me."
Whatever was said to Erdogan, Halkbank was indicted last fall for fraud, money laundering, and sanctions violations after a negotiated settlement fell apart.
While some critics have charged that Bolton's stories will weaken Trump's position on the world stage, Bolton shot back he's "not telling Vladimir Putin anything that he doesn't already know -- and it's telling the American people something they may not be aware of."
"The North Koreans, as perhaps with Iran and China and Russia as well, think that if they can separate Trump from his advisers, they can get him to make a deal. ... They see him as somebody who's fundamentally not aware of the trade-offs he's making," Bolton added.
What Bolton says Trump is like
That drive to make a deal that would burnish his image as a deal-maker and support his reelection was dangerous, according to Bolton.
"There really isn't any guiding principle that I was able to discern other than what's good for Donald Trump's reelection," Bolton told Raddatz. "There's no coherent basis, no strategy, no philosophy, and decisions are made in a very scatter-shot fashion, especially in the potentially mortal field of national security policy. This is a danger for the republic."
Beyond his critiques of Trump's foreign policy or philosophy, Bolton takes aim at Trump's decision-making, at the man himself: "The president's thought process is a random walk that never stops. I mean, it's like a random walk meets Groundhog Day."
"I couldn't tell from day to day in the White House what was gonna happen," he added, calling the president "stunningly uninformed" and saying it was "very difficult, therefore, to have sustained conversations about policy development over a period of time."
According to Bolton, Trump spoke about as much as he listened during his intelligence briefings, which were far less frequent than other presidents. He listened to unknown outside advisers who gave him, what Bolton describes as "inaccurate" information that was not vetted by the professional staff, and he could not grasp "bits of history that help to inform the current context of a lot of situations. And we just never made headway on many of them," Bolton said.
"It's one thing to be erratic and impulsive and episodic and anecdotal on day-to-day stuff. It's when you get into crisis situations or very high-stakes circumstances where it becomes not only important, but potentially dangerous if the president doesn't maintain the focus on what's in front of him," Bolton said.
Raddatz pushed back on Bolton's characterization, pointing to his own past praise of Trump as a deal-maker with an "outstanding" ability to "size up" opponents.
Bolton said he didn't "particularly" believe that at the time, but had to defend the president and put "the triumph of hope over limited experience at that point."
This report was featured in the Monday, June 22, 2020, episode of “Start Here,” ABC News’ daily news podcast.
"Start Here" offers a straightforward look at the day's top stories in 20 minutes. Listen for free every weekday on Apple Podcasts, Google Podcasts, Spotify, the ABC News app or wherever you get your podcasts.