The presidential candidates who looked worst after Joe Biden’s cracking Super Tuesday performance were not Bernie Sanders, Elizabeth Warren and Mike Bloomberg. They were John Kasich, Ted Cruz, Marco Rubio and Ben Carson, who could not manage, before Super Tuesday in 2016, to prevent the hostile takeover of the Republican Party by a divisive hothead.

That is a cheap shot, but only because it is unfair to single out four men in a party whose entire political and legislative leadership capitulated with minimal resistance to a populist candidate who openly hated them. In the 2016 Republican primaries, Donald Trump did not win a majority of the vote in any state until April 19. Some type of early, concerted action by Republican candidates and leaders might have prevented Trump’s rise — or at least offered a serious example of resistance to future Republicans.

How do we know this would have been possible? Because it just happened in the other party. Democratic leaders have also seen the rise of a populist candidate who openly hates them. But in this case, two center-left candidates — Amy Klobuchar and Pete Buttigieg — sacrificed their presidential ambitions and endorsed Biden for the sake of their party. That is the political equivalent of two soldiers jumping on a grenade to save their platoon. And on Super Tuesday, self-identified Democrats in large numbers — by a 20-point margin in North Carolina, a 30-point margin in Virginia and a 50-point margin in Alabama — supported a self-identified Democrat over a self-identified socialist revolutionary.

We do not yet know if this effort to preserve the Democratic Party will succeed. But one thing is certain: The Democratic Party still exists as an institution. Prominent Democratic politicians still think that conspicuous loyalty to their party will bring respect and future preferment. Many Democratic voters clearly prefer their traditional identity and are refusing to live inside a demagogue’s distorted dream.

Democrats do have an advantage over their Republican counterparts: an immediate example to recoil from. The Trump takeover of the GOP demonstrates that some political choices are difficult to unmake, like trying to un-stir cream from your coffee. Because partisanship is so powerful, many Democrats would feel compelled to support a President Sanders the way Republicans now support President Trump. And this would likely turn their partisan duty into the justification of one man’s eccentricities and extremism. Whatever a President Biden’s flaws may be, defending him would at least be the defense of a distinctly Democratic cause.

The Democratic Party is blessed with an abundance of rational partisans. And a subset of that blessing is this: The most loyal constituents of the Democratic Party — African Americans — tend to be prudent and practical voters. In contrast, the most loyal constituents of the Republican Party — white evangelical Christians — have been easy converts to a personality cult.

There is, of course, diversity of opinion within any group of voters. But the collective role played by African American voters in this election has been particularly decisive. It was black voters — first in South Carolina and then in Virginia, Texas, Tennessee, North Carolina and Alabama — who saved Biden’s candidacy, saved the possibility of a center-left Democratic Party and saved the hope that U.S. politics can consist of something more than anger and grievance.

Some African American support for Biden is based on familiarity. When people in crowds chant, “We know Joe!,” they are saying they have seen his empathy and decency demonstrated over decades. That type of trust cannot be bought with paid advertising.

But apart from affection for Biden, African American voters have a reputation for favoring center-left, establishment candidates over liberal alternatives. They tend to view the stakes of certain political results — such as the reelection of a president who feeds racism as a political strategy — as very high. And their broad reaction to this heightened sense of risk is pragmatism in avoiding destructive outcomes. This is a healthy political instinct.

Contrast this again with the GOP’s most loyal cohort, white evangelicals. They also tend to view the stakes of politics as very high, but their reaction to risk has been to trust a profane, cruel, lawless strongman to defend their interests. This has enabled a presidential assault on institutions that frustrate his will.

Often in U.S. history, it has fallen to African Americans to clarify, articulate and embody America’s partially realized creed. Once more have they defended a humane, democratic liberalism when others did not find it important or convenient.

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