If Donald Trump wants to return to the White House, he has to get serious about winning the “ground war.”

Social-media memes didn’t elect him in 2016 — his relentless schedule of campaign rallies did.

But this month the Republican nominee is taking a break from the campaign trail, while the Democrats bask in the publicity of their national convention.

Is this wise?

Trump held 27 rallies in August 2016, according to CNBC, yet this time he has only a handful.

Instead he’s returned to X, the social-media site formerly known as Twitter, for an interview with its larger-than-life impresario, Elon Musk.

It’s a move straight out of the playbook that failed to get Ron DeSantis the Republican nomination.

The Florida governor kicked off his doomed campaign with a Musk interview in May of last year.

Social media has a place in 21st-century campaigning, but it isn’t where elections are won.

Then again, before Trump’s stunning upset eight years ago, the conventional wisdom was that rallies didn’t win elections, either.

They were Trump’s secret weapon — a tactic so old-fashioned that Hillary Clinton’s top-dollar political professionals didn’t dream it could change the course of the contest.

The top-dollar consultants were wrong, and Clinton paid for her campaign’s complacency.

She expected to win an “air war,” with her side’s 2-to-1 fundraising edge over Trump’s effort translating into overwhelming dominance in television ads.

But by showing up in places no nominee from either party had set foot in for a generation, Trump convinced voters in the vital Rust Belt battlegrounds that he cared about Americans the elites had written off.

Whether or not Wisconsinites, Pennsylvanians and Michiganders got to attend a Trump rally in person, the candidate’s personal presence in some of the less fashionable zip codes in their states made an impression — in a way slick television commercials didn’t.

Trump couldn’t run a ground war the same way in 2020, of course, amid COVID fears and lockdowns.

Without the advantage his rallies gave him, he lost.

Joe Biden was an absentee on the campaign trail, much as he’s been an absentee as president, too.

In the circumstances, it didn’t matter — and Biden might have hoped he could win the same way this November even without COVID to cover for him.

That was a vain hope even before the president’s debate meltdown.

Trump wouldn’t have had to barnstorm the battleground states with anything like the energy he marshaled in 2016 to outdo Biden, given the president’s decrepitude.

But now that Kamala Harris is the Democratic nominee, Trump can’t afford to be any less vigorous than he was when he took on Clinton.

He’s eight years older, but his stamina remains remarkable — all the more so for a man who was nearly slain by an assassin’s bullet just a month ago.

He had the vim to deliver a 92-minute acceptance speech at the Republican convention, longer than some of his listeners could last.

The question now is less whether Trump is capable of campaigning like it’s 2016 than whether he sees a need to.

He has tools at his disposal now that he didn’t have then, chief among them a better-funded, more professional campaign team.

But the best team that money could buy only led Clinton to defeat.

Whatever new strengths Trump thinks he’s acquired, he’d be reckless to rely on them rather than on the one thing that worked before: going straight to the voters.

That means not only holding more rallies but also augmenting his operation in the battlegrounds, where early yet persistent reports say Republican organizing lags behind the Democrats’.

Harris’ party perfected a new kind of campaign in 2020, just as Trump reinvented an old one with his in-person politicking four years before.

The Democrats head into the final phase of this year’s contest with a strategy for mail-in and early voting that Republicans were utterly unprepared for four years ago.

Has the GOP since caught up?

Trump can hardly count on it — not after the party’s lackluster results in the 2022 midterms.

Only once in the past 32 years has a Republican received more votes in a presidential contest than the Democrat.

Except for George W. Bush’s re-election in 2004, Democrats have won the popular vote every time since 1992.

It’s not just recent polls that make Trump out to be the underdog in this race — the underlying electoral makeup of the country favors Democrats for the White House.

Trump defied polling and history alike when he demolished the Democrats’ “blue wall” in the industrial heartland two cycles ago.

He did it by just by showing up, in the flesh, which is exactly what he needs to do again.

Daniel McCarthy is the editor of Modern Age: A Conservative Review and editor-at-large of The American Conservative.