“This is not your father’s Republican Party,” President Biden likes to lament as if he misses the landslide wins of Presidents Reagan, Nixon, and Eisenhower. As the election data roll in, we’ll learn if President Trump is moving the GOP back to those days of electoral dominance or if he’s just sunk the party’s chances of winning for the foreseeable future.

“We have a big tent in this party on everything from national security to economic policy,” Trump’s running mate, Senator Vance, said in his speech to the Republican National Convention. “But my message to you, my fellow Republicans, is we love this country, and we are united to win.” That might have been met with praise from Mr. Biden, if his statement at the 2011 Washington Ideas Forum is to be believed.

“In my view,” said Mr. Biden, then vice president, “we need a strong Republican Party. We need a Republican Party that’s united.” That the party has united around Trump, however, wasn’t what he had in mind. He might prefer something more along the lines of the longest-serving House minority leader, Bob Michel, an Illinois Republican.

In 1995, Michel described the speech he gave to each freshmen Republican class. “Every day,” he told Time, “I wake up and look in the mirror and say to myself, ‘Today you’re going to be a loser.’ And after you’re here a while, you’ll start to feel the same way. But don’t let it bother you. You’ll get used to it.”

Trump’s message in 2016 was far more persuasive than losing. “We’re gonna win so much,” he told supporters in August of that year, “you may even get tired of winning. And you’ll say, ‘Please, please. It’s too much winning.’” To win, though, he has to inspire more voters to the polls than Vice President Harris. In addition to outreach, he reversed his 2020 condemnations of early voting, encouraging supporters to bank their votes before Election Day.

Early numbers show those voters turned out, but Republicans tend to vote on Election Day. There may not be enough of them left to sustain Trump’s leads or overcome deficits; so, victory will depend on how much he expanded his support. One place he may have done so is with Hispanic voters. A CBS News poll in August found that group giving Ms. Harris “the smallest margin” this century of any Democrat.

Other parts of the Democratic coalition, including working-class union voters like the Teamsters, have been drawn in by Trump’s message. In a poll released last month, GenForward found that 26 percent of Black adults between 18 and 40 said they’d vote for Trump. If that’s even close to true, it would be the largest percentage for a Republican since 1960, when President Nixon earned more than 25 percent of that demographic.

In November of 2022, after the GOP fell short of expectations in the midterm elections, I explained in the Sun why Republicans had to get out beyond the conservative media bubble to grow their base. “Preaching to the choir,” I wrote, “is a good strategy to land contributions, book deals, and a Fox News Channel consulting gig, but not to win elections.”

I pointed out that the Republican candidate for president had won the popular vote “just once in the last eight tries, stretching back to 1992. Democrats have 48 million registered voters nationwide, an advantage of 11.6 million over Republicans. Democrats cross the 50 percent threshold in seven states worth 73 electoral votes compared to three states for Republicans worth 22.”

Trump learned that whipping up his base alone wasn’t enough in 2020. In the four years since, he has tried to expand his appeal. He’s also had some defections, such as Vice President Cheney and his daughter, Congresswoman Elizabeth Cheney. And Vice President Pence. We’re about to learn if they helped Ms. Harris more than the endorsement of the Democrat Robert F. Kennedy, Jr., and other first-time Republicans helped Trump.

In addition to appearing on any media outlet that will have him, Trump has set up the MAGA big top in Democratic Party bastions like New Jersey, Manhattan, the Bronx, and Philadelphia. Often, Trump’s loose lips have meant calling for the guys who sweep up after the elephants. Other times, critics have mocked the trips as pointless. Social media posts of beaming converts will mean nothing if Trump falls short today.

Mr. Biden may wax nostalgic about “your father’s Republican Party,” but he never much cared for it at the time. Trump won’t win anything like those landslides. After decades in the wilderness, though, just winning the popular vote would feel like a triumph for Republicans — while falling short could begin a long period of looking in their mirrors and getting used to seeing losers.