In the end he had two choices. One: Brace himself for a war in the Republican primary with the Bannon-backed Kelli Ward that he’d be lucky to survive, only to then have to fight another war with a formidable Democrat in Kyrsten Sinema in the general election. Given the piss-poor state of his polling in Arizona, what are the odds he’d manage to win both? Twenty-five percent at best? Maybe less with Trump hooting at him from the sidelines?

Two: Go the Bob Corker route and spend the next 15 months free to vote his conscience and to rip Trump to his heart’s content. An easy call, really.

It’s Trump’s party now:

He told The Arizona Republic ahead of his announcement that he has become convinced “there may not be a place for a Republican like me in the current Republican climate or the current Republican Party.”

Flake said he has not “soured on the Senate” and loves the institution, but that as a traditional, libertarian-leaning conservative Republican he is out of step with today’s Trump-dominated GOP.

“This spell will pass, but not by next year,” Flake said…

“Here’s the bottom line: The path that I would have to travel to get the Republican nomination is a path I’m not willing to take, and that I can’t in good conscience take,” Flake told The Republic in a telephone interview. “It would require me to believe in positions I don’t hold on such issues as trade and immigration and it would require me to condone behavior that I cannot condone.”

He’s planning to speak on the Senate floor within the hour as I write this about that, ahem, “behavior.” His reelection strategy never made sense: He’s a small-government conservatarian, which alienates Democrats, and he’s also the most outspoken Trump critic in the GOP caucus, which alienates populist Republicans. He had no path. As a man of principle, he apparently resolved earlier this year to do what his conscience told him to do and to let the chips fall where the may electorally. And they fell … poorly. That makes me wonder, is Flake stepping aside voluntarily, for the good of the party in the hope that this will clear the way for a more electable establishment alternative to Ward? Or was he pushed off the cliff by McConnell and the NRSC, who took a hard look at the polls and were convinced he couldn’t win? Either way, handing the seat to Ward or Sinema may have been equally unpalatable options for Flake. The only way to prevent it was to create a path for a third candidate. Which meant retirement.

To all appearances he was still planning to run for reelection as recently as a week ago. Condoleezza Rice appeared at a fundraiser for him within the last few days and Flake sounded like he was intent on forging ahead in an interview with the Weekly Standard:

Flake’s standing in the polls and his devil-may-care attitude toward criticizing Trump have prompted some speculation that he may not even stay in the race until the end. I asked Flake if there was any truth to rumors that some Republicans in Washington have encouraged him to step aside so a Republican who’d have an easier time of winning the primary and the general could run. “That sounds like somebody from the other camp spreading rumors to me,” Flake replied, which sounded like a denial, but didn’t precisely sound like the word no.

So is he 100 percent committed to staying in the race? “I had a week where my break coincided with my kid’s day off. Instead I’m bouncing back and forth from California to have a fundraiser with Marco Rubio. I’ve got one with Condoleezza Rice next week. I’ve got four or five in between. That doesn’t sound like a candidate ready to hang it up,” Flake says.

And now he’s hanging it up. “Salon conservatives” are in mourning but Democrats now have their first real pick-up opportunity of 2018. Corker’s seat was always going to be a heavy left for them in a red state like Tennessee but a Sinema/Ward race in purplish Arizona is perfectly winnable. Stand by for Flake’s floor speech, which will probably be thick with Trump-bashing, whether direct or implied. I’ll post the clip below as soon as it’s available.

Update: Yep, he’s torching Trump. A taste:

Maybe Flake had “Corker envy.” So long as he was still running for reelection he couldn’t criticize Trump as freely as he wanted to. If he felt obliged to speak up while remaining in the race, that would all but guarantee Ward won the primary next year which in turn would guarantee that unpalatable Ward/Sinema election. To say what he felt he needed to say and to give the GOP establishment a fighting chance in Arizona next spring, he had to quit.

One big difference between him and Corker: Flake has been a Trump critic since the beginning. Corker’s found his nerve only within the last few months.

Update: Here’s the transcript of Flake’s floor speech. No holding back:

If I have been critical, it not because I relish criticizing the behavior of the president of the United States. If I have been critical, it is because I believe that it is my obligation to do so, as a matter of duty and conscience. The notion that one should stay silent as the norms and values that keep America strong are undermined and as the alliances and agreements that ensure the stability of the entire world are routinely threatened by the level of thought that goes into 140 characters – the notion that one should say and do nothing in the face of such mercurial behavior is ahistoric and, I believe, profoundly misguided…

We were not made great as a country by indulging or even exalting our worst impulses, turning against ourselves, glorying in the things which divide us, and calling fake things true and true things fake. And we did not become the beacon of freedom in the darkest corners of the world by flouting our institutions and failing to understand just how hard-won and vulnerable they are.

This spell will eventually break. That is my belief. We will return to ourselves once more, and I say the sooner the better. Because to have a heathy government we must have healthy and functioning parties. We must respect each other again in an atmosphere of shared facts and shared values, comity and good faith. We must argue our positions fervently, and never be afraid to compromise. We must assume the best of our fellow man, and always look for the good. Until that days comes, we must be unafraid to stand up and speak out as if our country depends on it. Because it does.

Update: Here’s the speech.