It is not irrational speculation. Americans have a history of sticking with flamboyant politicians with more than a passing relationship with the criminal justice system, from Marion Barry in Washington, D.C., to Edwin Edwards in Louisiana. Trump is a character from a similar mold, with an even tighter grip on his followers that verges at times on the quasi-mystical. At another point in his political life, perhaps Trump might have turned this case into rich fodder for a comeback.

Not now. For all his unusual strengths, Trump is defined these days more by his weaknesses — personal and political deficiencies that have grown with time and now figure to undermine any attempt to exploit the criminal case against him.

His base of support is too small, his political imagination too depleted and his instinct for self-absorption too overwhelming for him to marshal a broad, lasting backlash. His determination to look inward and backward has been a problem for his campaign even without the indictment. It will be a bigger one if and when he’s indicted.

Trump has been unusually resilient against scandal over the years thanks to the unbreakable loyalty of voters who see him as their champion in the arena. My colleagues David Siders and Adam Wren reported that Republicans expect Trump to get a short-term boost from the indictment because it will energize his core supporters. That is probably true.

But those supporters are a minority of the country, as Republicans have learned the hard way several times over. Stimulating Trump’s personal following was not enough to save the House for his party in 2018 or to defend the White House and the Senate in 2020, or to summon a red wave in 2022.

Trump needs to grow his support, not merely rev up people who already care deeply about his every utterance and obsession. It is not likely that many Americans who are not already part of Trump’s base will be inspired to join it because they feel he is being mistreated by Manhattan District Attorney Alvin Bragg.

Personality-cult politics, on its own, has never really been a winning model for Trump. At his strongest moments, he has convinced voters that Trumpism is about far more than Trump — that it is not merely a jumble of racist and sexist outbursts and weird grudges against the likes of Rosie O’Donnell and Megyn Kelly, but a worldview that might transform America. Trump’s great success in 2016 was his ability to persuade tens of millions of Americans to see him as a stand-in for their own grievances and yearnings.

The most memorable moment in his convention speech that year was when he declared the United States was horrifically broken and “I alone can fix it.” His critics rightly saw it as a telling display of a narcissistic and authoritarian mindset.

But the bit in that speech that best conveyed Trump’s appeal was one taking aim at the Clinton catch phrase, “I’m With Her.” Trump’s rejoinder: “I choose to recite a different pledge. My pledge reads: ‘I’m With You.’”

Suddenly Clinton was the self-absorbed one and he was the tribune of plebs.

It is hard for a candidate to tell voters “I’m with you” when he is mainly consumed with narrow, personal complaints and crackpot conspiracy theories. Plenty of Americans can see themselves in an older white man scorned by liberals and the media for his crude manner and bigoted ideas. Fewer are likely to see themselves in a wealthy husband paying hush money to conceal his debauched sex life and whining about the unfairness of his circumstances in every public outing.

What is the great cause of Trump’s 2024 campaign, aside from Trump himself?

The politicians who best weather scandal are the ones who tell and show voters that they are doing the people’s business while opponents stew in lurid trivia.

Bill Clinton survived impeachment and finished his second term as a popular president by persuading voters that he was balancing budgets and keeping them safe while Newt Gingrich and Ken Starr pilfered his underwear drawer. More recently, Ralph Northam overcame a blackface scandal and completed his term as governor of Virginia by promising to devote himself to fighting racial inequality. (One civil rights leader in Richmond captured the appeal of this approach, telling the Christian Science Monitor of Northam’s critics: “People can continue to talk about yesterday. I want to talk about tomorrow.”)

Abroad, Benjamin Netanyahu endured as the leader of Israel’s political right while fighting corruption charges, and returned in December to serve as prime minister, by arguing to voters that he was his country’s only true steward of national security and the allegations against him were a left-wing plot — a distraction from things that really matter.

Trump does not have much to say about things that really matter.

Unlike the Trump of 2016, who shattered the policy orthodoxy of the GOP establishment and reshaped the party’s ideology in his own image, the Trump of today contributes nothing new to the Republican agenda.

He has fallen behind the times even compared to his current and former allies. In South Carolina, he ridiculed electric cars standing beside Gov. Henry McMaster, a 75-year-old loyalist who like other Republican governors has promoted his state as a hub for EV manufacturing. When the Supreme Court abolished the constitutional right to abortion, Trump largely declined to address the most significant consequence of his own judicial appointments. It was Mike Pence, his excommunicated vice president, who hailed the decision as a transcendent victory for the right to life and vowed to carry forward the battle against abortion.

On the war in Ukraine, Trump speaks for a faction of the GOP when he derides it as a waste of money that is not America’s problem to solve. He is alone among Republican candidates in threading that view with admiring commentary about Vladimir Putin. His hostile view of China — a subject on which he reshaped American political discourse — remains compromised by his tendency to talk about Xi Jinping like a golfing buddy.

None of this is to say that Trump cannot win the Republican nomination, or even the presidency. Elections are unpredictable. But it is past time to give up the idea that stoking the anger of Trump’s diehard fans is a victory unto itself.

If each scandal or blunder binds 99 percent of his base closer to him and unsettles 1 percent, that is still a losing formula for a politician whose base is an electoral minority. Trump cannot shed fractional support with every controversy but make it up on volume.

The question before Republicans is whether they need another lesson from the electorate in the perils of running on a version of Trumpism that is all about Trump. A campaign about Jan. 6 and Stormy Daniels is not one that is likely to end well for Republicans.

That is a mortal problem for Trump’s candidacy.

He alone can fix it.