The stars are aligning for Joe Biden. The coalition that is abandoning Bernie Sanders for the dull but reliable war horse could put the former vice president across the finish line in November.

Democrats flipped 41 House seats in 2018 and did well in Virginia, Kentucky, Louisiana and Mississippi last year with moderate candidates offering solutions to middle class problems. They defeated Republicans who ran on President Trump’s campaign rally staples — cultural issues, abortion and gun rights.

Many of the voters who delivered for those Democrats — African-Americans, college-educated women and suburban middle class — rejected Sens. Sanders and Elizabeth Warren for Mr. Biden. Ms. Warren and the #MeToo movement may want to blame sexism, but the Democratic base has grown older and more moderate than the pitch of hard-left politicians. They reject socialism and gender-based politics — just as they do Mr. Trump’s anti-political correctness and nativism.

Disaffected blue-collar voters are a declining share of the electorate, but the really bad news for Mr. Trump is how much voter turnout is growing among Mr. Biden’s coalition. On Super Tuesday, for example, participation was up 70 percent and 40 percent in Virginia and Texas, respectively, over 2016. 

Contrary to thinking at the White House, the COVID-19, economy, bad messaging and inaction on critical middle-class issues will hurt Mr. Trump big-time in November. Paradoxically, if he looks to the disappointed among Mr. Sanders’ base, he can still win.

America’s experience with the Spanish flu a century ago provides critical clues about how the epidemic will play out this spring and summer. Then as now the illness was spread by respiratory droplets and primarily killed by inflicting pneumonia and other complications — especially on the old and other already vulnerable. State and local politicians and health officials were the frontline actors.

Philadelphia acted slowly and initially downplayed the coronavirus — it allowed a Liberty Loan parade drawing 200,000 people and that filled hospitals within 72 hours. St. Louis did best by openly addressing the crisis and moving quickly to implement individual quarantines and banning public gatherings.

When the coronavirus first arrived, Washington state and other jurisdictions should have moved faster, but the Trump administration sent a confused message about the need for decisive action — now it is vulnerable. As infections and deaths mount, the president will get the blame as the great divider.

The news media, pundits and the Democratic Party establishment offer Mr. Biden as the Great Unifier. That’s hypocritical — Democrats denied the legitimacy of Mr. Trump’s election, endorsed Rep. Adam Schiff’s witch hunt and denied the president the opportunity to bring the country together.

Actions in the present count more than historical gaffes. Mr. Biden’s flip-flopping on China and abortion, and his lethargic demeanor won’t give Mr. Trump enough ammunition if the country is suffering from fever.

China and Italy are already in recession, and U.S. growth will sink significantly for the first half and won’t rebound enough in time for the fall campaign.

Middle-class incomes on paper have recovered from the Great Recession, but housing, health care and higher education tuition and debt are unaffordable. Candidate Trump and his Republican allies promised to address those but have a record no better than the Washington Redskins.

Still, there’s Mr. Trump’s final opportunity. As the incumbent, he can send a lightning bolt through the Biden playbook and send him down in flames.

In voting so far, Mr. Sanders has done well with Latinos but young folks who are terribly burdened by student debt have not been turning out in large numbers. That’s where the potential additional votes are, and he should put Larry Kudlow’s economic brain thrust to work on a solution.

Washington is the principle creditor — the federal government now holds or guarantees 90 percent of the $1.6 trillion college debt. Mr. Trump can send Congress a bill to wipe away those loans and buy up the remaining 10 percent by issuing new bonds and advocate tuition reforms. Capital markets are eager to absorb the bonds, or the Federal Reserve could purchase them to give the economy a giant boost.

Democrats in Congress don’t want to forgive the loans of six-figure Wall Street bankers, physicians and attorneys at big law firms, but Mr. Trump should force them to do the heavy lifting of whittling the bill down — make them take heat for voter disappointment or their inaction.

Debt forgiveness would tap a huge vein of voters Mr. Biden didn’t win from Mr. Sanders and could put the president over the top.