Sans usual campaign events, what should Joe Biden do?

Joe Biden took another step toward locking up the Democratic nomination on Tuesday. His lead in delegates has begun to look insurmountable.

But now the presidential race enters uncharted territory due to the coronavirus crisis. Tuesday’s three primaries may be the last large campaign gatherings for a month or more; at least five other states are postponing their primaries.

The normal rituals of a campaign — giant rallies, town meetings, barnstorming tours — have been canceled. The Democratic and Republican political conventions, scheduled for July and August, may be next.

So what should Biden do? Here’s my advice.

One: Be presidential. Biden is best when he contrasts himself with President Trump. His strong suit is his eight years as President Obama’s vice president — but he has to answer for old votes from his 36 years in the Senate before that.

His strongest moment in his one-on-one debate with Bernie Sanders on Sunday was his crisp answer on how he’d address the coronavirus crisis as president.

“First of all, I have to take care of those who, in fact, are exposed or likely to be exposed to the virus, and that means we have to do testing,” he said. “Secondly, I would make sure that every state in the union had at least 10 places where they had drivethrough testing arrangements. I would also, at this point, deal with the need to begin to plan for the need for additional hospital beds . ... But we have to deal with the economic fallout quickly, and that means making sure the people who in fact lose their job, don’t get a paycheck, can’t pay their mortgage, are able to pay it.”

David Axelrod, Obama’s former political strategist, has often been critical of Biden’s campaign, but he pronounced that answer “sensational.”

In the weeks ahead, expect Biden to praise the Trump administration’s actions to stem the epidemic when they work, but draw clear differences on Trump’s economic response.

Two: Reach out to Sanders and his voters.

The race for the nomination isn’t over unless Sanders drops out. The Vermont senator has every right to compete for votes, especially with primaries on hold in New York, Ohio, Georgia and other states.

But that shouldn’t stop Biden and Sanders from reconciling. In Sunday’s debate, Sanders was uncharacteristically restrained in his critiques of Biden’s positions. He even said Biden’s “heart is in the right place.”

Biden, conversely, criticized Sanders’ “Medicare for All” plan and noted that Italy’s single-payer system hasn’t coped well with coronavirus.

Instead, he could have emphasized what he and Sanders share — a commitment to universal health care, for example.

Biden’s aides argue that he’s a moderate Democrat, but he’s more progressive than any previous Democratic nominees, including Obama and Hillary Clinton.

Like Sanders, Biden wants to impose big tax increases on the wealthy — although not as big. Like Sanders, he wants to make college tuition-free for most families, although Biden’s plan has an income cap of $125,000.

Those differences are not unbridgeable. Each candidate has said he will support whoever wins the nomination.

Three: Even without rallies, a candidate can make news.

In Sunday’s debate, Biden grabbed headlines by promising to choose a woman as his running mate.

Four: Get plenty of rest. This year’s campaign has produced the mystery of the two Joe Bidens.

He’s long been a gaffe machine, prone to stumble over his words or make an impolitic remark.

But he also can be forceful and crisp. He can even be eloquent, as he was in his victory speeches after South Carolina and Super Tuesday. He rarely stumbles in interviews or impromptu exchanges with reporters.

Claims by Trump and his supporters that Biden, 77, suffers from some form of dementia are malicious and don’t stand up.

And any voter who watches a highlight reel of Biden’s flubs should compare it to Trump’s stumbles and lies, which are at least as alarming — and the president is only 74.

Besides, Biden readily admits that he’s gaffe-prone.

Still, any candidate in his 70s should know his limits. In 1984, President Ronald Reagan, then 73, trimmed his reelection campaign appearances to one a day, and mostly read set-piece speeches.

Reagan won 49 states.