Sen. Jeff Flake (R-Arizona) in 2015. (Laura Segall for The Washington Post)

Sen. Jeff Flake (R-Ariz.) is one of the few elected Republicans to defy the pull of partisanship in the presidential election. He continues to denounce Donald Trump and withhold his support.  On “Face the Nation,” he refuted the excuse that Trump is different in private and public. “If you could govern in private, I guess that would be okay, but you can’t,” Flake said dryly. He went after Trump for “the statements that he’s making, particularly here in Arizona, the statements he made right out of the gate when he got into the campaign about those crossing the border being rapists and whatnot.” Flake added, “That just doesn’t sit well, and then to refer to a judge born in Indiana as a Mexican in a pejorative way.” Flake explained:

These changes, like I said, not only have to be tone and tenor. Some positions he’s taken need to change. And he has got to have a more serious immigration policy than simply saying we’re going to build a wall and make Mexico pay for it.

His position with regard to NATO and that security arrangement we have with European countries, that needs to change. The Muslim ban seems to be walked back, but we’re not sure where he’s landed there. And so there’s a number of these positions that need to change as well. . . . We have got to trade if we want economic growth. And [the Trans-Pacific Partnership] is important, not only because of trade and economic growth. Geopolitically and for our security, it’s extremely important. We want Southeast Asian countries in particular to be in our trade orbit, and not just China’s.

And so these are important things that — it would be great if we could do just bilateral trade agreements. That’s not the world today. These countries have choices and we’re going to be left behind if we don’t enter multilateral trade agreements.

In addition to dismissing populist hooey about immigration and trade and standing tall on national security (including economic security), Flake insisted Trump’s temperament is unacceptable: “Well, when you have somebody who says what he said to this Gold Star family, when he has made the statements with regard to Hispanic Americans, there are a number of other statements with regard to women. These things have to change.” He added, “You can’t go on, and then expect that you’re going to be president of the United States when you make statements like that. That’s why some of us, I believe, need to push back and say that we need a more responsible campaign. And we haven’t seen it so far.”

Trump, of course, cannot change, and we suspect Flake knows that. Flake is not conning  the voters — or himself.

Contrast that with Sen. Tom Cotton (R-Ark.), once thought to be an up-and-comer for Republicans. As an Army vet who has fought in the war against Islamic terror and someone who regularly touts the importance of our NATO alliance against Russia, Cotton inexplicably cannot bring himself to step away from Trump — even as he is unable to vouch for Trump’s fitness as commander in chief. Asked about Trump, Cotton ridiculously argued that “the media is obsessed with Donald Trump.” Well, he is running for president of the United State. “Face the Nation” host John Dickerson wouldn’t let Cotton shift the conversation back to Hillary Clinton:

DICKERSON: [S]ince Donald Trump is the nominee of your party, and you spoke at the convention about him, you said help is on the way, when, in the future, Donald Trump is in the office of the presidency, do you think he has the temperament to handle those lonely decisions that a president makes?

COTTON: John, I’m confident, if the American people elect Donald Trump, and they elect a Republican president, that America will be safer and stronger in the world, our streets will be safer and our country will be more prosperous.

DICKERSON: You said elect a Republican president. You mean elect a Republican Congress.

Do you think the Congress will help keep him in check?

COTTON: John, the Congress plays a central role in our constitutional structure.

Cotton cannot vouch for Trump as commander in chief or honestly say the Congress can keep in check. So why in the world is he endorsing him for president? Cotton, whose ambitions in the House led to an immediate Senate run, plainly wants to advance his career. Unlike Flake, however, he is not willing to withstand the right’s ire to stay true to his beliefs and to resist enabling a man who has vowed to order the military to commit war crimes. Cotton, no matter how eloquent or insightful on some issues, has failed the test of moral and political leadership. Cotton might be closer to many GOP hawks when it comes to national security, but from here on out many will prefer Flake — who is intellectually honest, decent and prioritizing country over party. Policy differences can be discussed and debated in good faith; they pale in comparison to these fundamental aspects of character. To the chagrin of many admirers, Cotton stands with political opportunists such as Newt Gingrich and New Jersey Gov. Chris Christie.

It is a sobering, albeit belated, revelation for some Republicans to recognize that agreement on issues is not the be-all and end-all of politics. Cotton might continue to be a successful senator and still offer credible policy arguments on a variety of issues. This, however, is not the same as possessing the wisdom and character required for high office or to lead a new chapter in the party’s history.

Cotton is not, alas, the future of the party; he’s representative of the sort of Republican politics — slavish partisanship, selective memory, unwillingness to stand up to the mob — that must fall by the wayside.