A rematch nobody wanted: But some big differences define Biden vs. Trump in 2024

Barring asteroids hitting the Earth before then, the presidential ballot in November is set to feature Joe Biden versus Donald Trump.

Again.

With Super Tuesday over, the rematch almost no one wanted now seems all but certain.

Trump's near-sweep of GOP contests in 15 states and one territory − with the exception of Vermont − put him within striking distance of enough Republican National Convention delegates to clinch the nomination. His last remaining GOP rival, former South Carolina Gov. Nikki Haley, is dropping out of the race.

Meanwhile, Biden's State of the Union address Thursday will launch his election-year agenda, with the preservation of democratic institutions once again the heart of his message.

That all sounds familiar enough, but the 2024 campaign is not simply a rerun of the original version four years ago. Changes in the candidates and the world are defining a different political landscape and creating new challenges, especially for Biden.

In his victory speech at Mar-a-Lago in Florida, Trump targeted Biden, calling him "the worst president in the history of our country" and adding, "Nov. 5, it's right around the corner." In his written statement, Biden focused on the general election, too. "Today, millions of voters across the country made their voices heard," he said, "showing that they are ready to fight back against Donald Trump’s extreme plan to take us backwards."

In recent months, the current president has begun lagging the previous one in national and swing-state polls.

What's different in 2024?

This time, it's incumbent vs. incumbent.

In 2020, Trump was the incumbent and Biden the challenger, with the freedom to criticize his opponent's record without having to defend one of his own.

Consider immigration. Trump used heated rhetoric to warn of the dangers of migrants and instituted harsh and controversial policies, including separating families at the border. In the 2020 campaign, candidate Biden promised a more humane approach that would be consistent with America's aspirational values.

Now, as the current resident of the White House, Biden owns the surging problems at the southern border.

In recent weeks, he has begun calling a record flood of asylum seekers there a "border crisis" and endorsed legislation that could close the border at times and expedite deportations. He no longer mentions an early priority, to create a pathway to citizenship for "Dreamers," those brought to the U.S. illegally as children.

Securing the border and controlling immigration gives Trump the biggest issue advantage over Biden, according to an NBC News poll taken in January. Those surveyed said by a yawning 35 percentage points that Trump would be better at handling it than Biden.

The issue continues to galvanize Republicans. In exit polls Tuesday, GOP primary voters in North Carolina and Virginia cited immigration as the most important issue, more important even than the economy.

Biden's foreign policy cred is under fire.

In 2020, Biden emphasized his foreign policy experience, while depicting Trump as a peril to U.S. alliances and interests in the world.

But the botched withdrawal of U.S. forces from Afghanistan in 2021, costing 13 U.S. service members their lives, shook the image of him as a steady leader. Now in the Mideast, his support of Israel's military response to Hamas' brutal attack six months ago has created a new crisis. The humanitarian catastrophe in Gaza has divided the Democratic Party and prompted protesters to disrupt events by Biden, first lady Jill Biden and Vice President Kamala Harris.

Advocates had urged Democrats to vote "uncommitted" to show their dissatisfaction with Biden's policy toward Gaza. On Tuesday, "uncommitted" received nearly 19% of the Democratic primary vote in Minnesota and about 8% in Colorado. It had received just over 13% in the earlier primary in Michigan.

Meanwhile, Trump has stayed largely silent about the conflict and its solutions − the privilege of challengers.

For some, Trump no longer seems quite so scary.

Trump hasn't toned down his rhetoric. But he lost his prime minute-to-minute platform when he was banned from Twitter in 2021, so fewer people now see his attacks, often delivered in all caps − perhaps a silver lining for him, politically speaking.

What's more, some voters dismiss language that might once have caused a stir. Just Trump being Trump, some say.

Even his indictment on 91 felony counts didn't cost him the nomination. Instead, it has galvanized his core support.

In Virginia exit polls, a negligible 2% of Trump voters said having the "right temperament" was the most important candidate quality for them. Far more important: More than 4 in 10 wanted a candidate who "fights for people like me." An additional third said they wanted one who "shares my values."

That said, a third of Republican primary voters in North Carolina and 40% of those in Virginia said Trump wouldn't be fit to be president if convicted of a crime. That's a significant red flag.

While court challenges and appeals have pushed back the likely dates for trials in federal court on charges of mishandling sensitive documents and seeking to overturn the 2020 election, jury selection in the New York case, on charges of making hush-money payments, is scheduled to start on March 25.

We're all older now.

Republicans spotlight every stumble by Biden, now 81, as evidence that he lacks the mental and physical acuity to serve as president. Democrats note that Trump, just four years younger at 77, is making missteps of his own, including confusing Nikki Haley with Nancy Pelosi, and referring to Barack Obama as the current president.

That's an issue for Trump to some degree. In North Carolina, 1 in 5 Republican primary voters said he didn't have the physical and mental health to be president. Three-fourths said he did.

For Biden, the issue is more troublesome. He already became the oldest president in U.S. history when he won in 2020, at age 78, though his age wasn't a dominant issue then.

Four years later, it is.

This article originally appeared on USA TODAY: Biden vs Trump, the rematch no one wanted. What's different this time.