(CNN) In an interview on "60 Minutes" Sunday , Jeff Flake, the Arizona senator whose lingering doubts about Supreme Court nominee Brett Kavanaugh led to his call for a one-week FBI investigation into an allegation of sexual assault and inappropriate behavior levied against the judge, acknowledged something very important (and sad) about the state of our politics: He would have never done what he did if he wasn't retiring at the end of this year.

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Here's the exchange between Flake and Scott Pelley of "60 Minutes:"

PELLEY: Senator Flake, you've announced that you're not running for re-election and I wonder, could you have done this, if you were running for re-election?

FLAKE: No, not a chance.

PELLEY: Not a chance?

FLAKE: No, no.

PELLEY: Because politics has become too sharp, too partisan?

FLAKE: There's no value to reaching across the aisle. There's no currency for that anymore. There's no incentive.

Remember what, exactly, Flake did. He didn't vote against Kavanaugh -- President Donald Trump's pick to take over the seat of retired Justice Anthony Kennedy. Flake actually voted FOR Kavanaugh -- giving the judge a favorable recommendation out of the Senate Judiciary Committee. All Flake did is say -- and I am paraphrasing: Given that Christine Blasey Ford and Deborah Ramirez have both made serious allegations against Kavanaugh (and Kavanaugh has denied them), shouldn't we hit "pause" for a week to allow the FBI if there is anything they can find that might shed light on all of this?

That's it. It's entirely possible that, at the end of this week-long investigation, Flake winds up voting for Kavanaugh -- and the judge is confirmed.

And yet, Flake admitted to Pelley that he would never even have considered engineering that delay on Friday if he had been trying to win a third term in the Senate. That's a tremendously revealing commentary about how Flake views the current state of the Republican Party.

And that state is this: Any apostasy -- ANY -- is punished. You do what the President asks you to do. The end.

Flake knows the penalty for wandering from the tribe well. He's retiring because of it.

In the spring of 2017, Flake wrote a book called "The Conscience of a Conservative: A Rejection of Destructive Politics and a Return to Principle." It was an absolute broadside against not only Trump but a Republican Party that accepted him with open arms. Wrote Flake in one particularly scathing passage

"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."

That book made Flake enemy No. 1 for Trump. "I love the Great State of Arizona" he tweeted in August 2017 . "Not a fan of Jeff Flake, weak on crime & border!" Trump went further than just some Twitter attacks: The President actually met with Republicans considering running against Flake in the 2018 primary. Trump's ire had a direct political impact on Flake. While the Arizona Republican had a decidedly conservative voting record, polls suggested he would start his reelection race as an underdog against the likes of Kelli Ward, a conservative state legislator who had lost badly in her previous primary challenge to Sen. John McCain.

Flake bowed to the inevitable in the fall of last year, announcing he would not run again in 2018. "If I have been critical, it's not because I relish criticizing the behavior of the President of the United States," Flake said in announcing his decision. "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 reality, of course, was that Flake, in criticizing Trump, had sought to execute a kamikaze mission. But he didn't destroy his target. Trump, in case you missed it, is still president. And not only that, but Trump is among the most popular Republican presidents -- among Republicans -- in history. If anything, Trump has become more popular among GOP voters since he became president. The Flakes of the party have felt that sting again and again over the past 18 months. If Trump supports you, you (almost always) win. If he doesn't, you don't.

Tribalism is all these days. To the point where the idea of asking the FBI to look into allegations made against a man aiming for a lifetime appointment to the nation's highest court is seen as a politically punishable offense. So much so that the only person with the courage to request it was chased into retirement by the president of his own party.