INSISTING THAT the highest priority is defeating President Trump, Sen. Bernie Sanders (I-Vt.) endorsed former vice president Joe Biden on Monday, followed by former president Barack Obama and Sen. Elizabeth Warren (D-Mass.) later in the week. The left and the center-left are coalescing. Now it is the turn of those further right who understand the threat Mr. Trump poses to join an ideologically broad anti-Trump coalition, which will require them, too, to suppress their quotidian ideological disputes with Mr. Biden.

This is not to say that Mr. Biden and his new surrogates have suddenly solved the Democrats’ progressive-establishment divide. “I don’t endorse Joe Biden,” Briahna Joy Gray, Mr. Sanders’s former national press secretary, tweeted Monday, demanding that Mr. Biden make big concessions to the left. Yet if Mr. Sanders’s supporters accept what he says about the threat Mr. Trump poses, they should be working to shore up the left wing of the anti-Trump coalition. Democratic voters chose Mr. Biden’s coalition-building strategy rather than Mr. Sanders’s ideological stridency. Everyone who understands the Trump threat must try to make the strategy work.

In his endorsement, Mr. Sanders stressed that he and Mr. Biden share concerns about wealth inequality, the minimum wage, climate change, health-care access and much else. Mr. Sanders will have to repeat his positive case for Mr. Biden, as well as his negative case against Mr. Trump, often in the coming months, underscoring that progressives can make real gains if they work with Mr. Biden.

The coronavirus pandemic is too serious to let the president hold freewheeling press briefings in real time, says Post media critic Erik Wemple. (The Washington Post)

While Mr. Biden will likely make additional overtures to his left flank, perhaps in the party platform, he should avoid shifting much further left to adopt the Sanders program, which has now failed twice in the Democratic primaries. He should leave space on his right for patriotic Republicans and right-leaning independents to join his camp.

As the covid-19 crisis shows, conservatives have just as much interest in competent government as progressives do. They should be appalled by Mr. Trump’s corrupt authoritarian instincts, as he uses his power to threaten and discriminate against companies he personally dislikes and as he directs government resources toward political cronies. His trade protectionism, which led to a massive farm subsidy program, is perhaps the most socialist policy any president has imposed in recent times. Those who care about a strong national defense should worry that he has severed ties with close allies and cozied up to foreign strongmen who mean the United States harm. Anyone who has ever worried about the national debt should be horrified at his lack of interest in fixing the government’s finances.

When Mr. Trump was last on the ballot, many on the right stayed quiet or found ways to justify supporting the GOP nominee, while even some on the left irrationally refused to back Hillary Clinton. The Democrats are on the way to nominating a Trump alternative who would be better on every score that really matters, and who has gone out of his way to avoid demonizing those who disagree with him on less fundamental issues. It is time for unity.

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