The Republican senator, who was a vocal critic of President Trump during the campaign, has penned a book entitled " The Conscience of a Conservative: A Rejection of Destructive Politics and a Return to Principle " that takes off after not only the President but also GOP leaders who, Flake alleges, have enabled the man in the White House for far too long. (The title is a throwback to Barry Goldwater's seminal " Conscience of a Conservative ," which was originally released in 1960.)

An excerpt of Flake's new book, which goes on sale today, ran in Politico on Monday . And it was packed with devastating lines for Trump, Senate Majority Leader Mitch McConnell and even Flake himself.

Here are the 11 most damning.

1. "Who could blame the people who felt abandoned and ignored by the major parties for reaching in despair for a candidate who offered oversimplified answers to infinitely complex questions and managed to entertain them in the process?"

This is as cogent -- and brief -- an explanation for the rise of Trump as I have seen. Trump capitalized on frustration and alienation with the two-party system. And he took advantage of that most basic part of human nature: When faced with the utter complexity of the world around us, we look for simple solutions to make us feel better. Trump's promise to immediately make everything better with a snap of his fingers appealed to all of the people in the country who felt overwhelmed/angry/anxious about the ever-mounting problems they faced on a daily basis.

2. "It was we conservatives who, upon Obama's election, stated that our No. 1 priority was not advancing a conservative policy agenda but making Obama a one-term president—the corollary to this binary thinking being that his failure would be our success and the fortunes of the citizenry would presumably be sorted out in the meantime."

This is a DIRECT shot at McConnell. In October 2010, he said this to National Journal : "The single most important thing we want to achieve is for President Obama to be a one-term president." It became a rallying cry for Democrats, who insisted that it revealed that Republicans had no intention of ever even trying to work with Obama, believing it in their political interests to oppose him and his proposals at every turn. Flake rejects this sort of zero-sum game thinking and, in the process, delivers a major slap at the Senate leader's political worldview.

3. "To carry on in the spring of 2017 as if what was happening was anything approaching normalcy required a determined suspension of critical faculties. And tremendous powers of denial."

Democrats have been shouting "THIS IS NOT NORMAL" about Trump's actions in office since, well, he got into office. Flake argues that they are right -- and that Republicans have been trying to explain away Trump's lack of normality for far too long. Inherent in this argument by Flake is that Republicans have long known what they are doing -- trying to normalize or ignore Trump's behavior because it was in their political interest.

4. "I've been sympathetic to this impulse to denial, as one doesn't ever want to believe that the government of the United States has been made dysfunctional at the highest levels, especially by the actions of one's own party."

Flake makes clear here that he is not blameless in all of this, attributing his slow waking-up to the dangers caused by Trump's actions in office to the fact that the mind tends to try to see what it wants to see.

5. "It would be like Noah saying, 'If I spent all my time obsessing about the coming flood, there would be little time for anything else.'"

In one sentence, Flake annihilates his -- and the broader Republican -- response to Trump's almost-constant controversial comments. Dismissing Trump's tweets by saying he didn't have time to read them was, Flake acknowledges, a massive cop-out. The tweets -- as reporters like me have long argued -- are the centerpiece of this administration since they reflect the actual thinking and mood of the President of the United States. Ignoring them isn't an option.

6. "Too often, we observe the unfolding drama along with the rest of the country, passively, all but saying, 'Someone should do something!' without seeming to realize that that someone is us."

The Constitution, Flake notes, enumerates that the job of oversight of the executive branch falls to the legislative branch. Which means that it's up to Congress -- even if it is Republican-controlled -- to ask hard questions about Trump and his administration. Abdicating that responsibility for political purposes is simply not acceptable, Flake argues.

7. "There was a time when the leadership of the Congress from both parties felt an institutional loyalty that would frequently create bonds across party lines in defense of congressional prerogatives in a unified front against the White House, regardless of the president's party."

Again, this is a shot at McConnell -- not to mention House Speaker Paul Ryan. Flake is making the case that Congress should be bigger than any one party or any one president. And that by walking away from its role as a check and balance on Trump, Republican leaders are putting party before country.

8. "If by 2017 the conservative bargain was to go along for the very bumpy ride because with congressional hegemony and the White House we had the numbers to achieve some long-held policy goals—even as we put at risk our institutions and our values—then it was a very real question whether any such policy victories wouldn't be Pyrrhic ones. If this was our Faustian bargain, then it was not worth it."

This line is the crux on which the whole piece stands. What Flake is doing is taking apart the argument at the heart of why so many conservatives supported Trump: Because he would enact something closer to their agenda than would Hillary Clinton. Congressional Republicans openly admitted in the run-up to the 2016 election that Trump's personal conduct was totally unacceptable to them but they were for him anyway because he would appoint more conservative Supreme Court justices, work to lower taxes and get rid of regulations. For that promise, Flake argues, Republicans gave up their principles. And the juice wasn't worth the squeeze.

9. "Meanwhile, the strange specter of an American president's seeming affection for strongmen and authoritarians created such a cognitive dissonance among my generation of conservatives—who had come of age under existential threat from the Soviet Union—that it was almost impossible to believe."

This reflects just how radically different Trump's views on Russia are from his party. The simple reality is that Trump represents a total break from the way the Republican party has positioned itself vis a vis Russia for more than three decades.

10. "We shouldn't hesitate to speak out if the president 'plays to the base' in ways that damage the Republican Party's ability to grow and speak to a larger audience."

Good advice but hard to follow given a) the size of Trump's megaphone and b) his repeated willingness to play to the base on everything from immigration to the media to, well, everything.

11. "We have taken our 'institutions conducive to freedom,' as Goldwater put it, for granted as we have engaged in one of the more reckless periods of politics in our history. In 2017, we seem to have lost our appreciation for just how hard won and vulnerable those institutions are."

"One of the more reckless periods of politics in our history." Those are very strong words coming from any politician but especially from a conservative Republican. And Flake's broader concern about fragility of our institutions amid all of this recklessness is chilling.