In another era, a politician would have walked away.

For decades, American elected officials facing criminal charges or grave violations of the public trust would yield their positions of power, if only reluctantly, citing a duty to save the country from embarrassment and ease the strain on its institutions.

Then came Donald J. Trump. The former president isn’t just forging ahead despite four indictments and 91 felony charges, but actively orchestrating a head-on collision between the nation’s political and legal systems.

The ramifications continued to accrue this week, when the fundamental question of the former president’s eligibility for office was all but forced upon a Supreme Court already mired in unprecedented questions surrounding Mr. Trump’s plot to overturn the 2020 election.

But the heated legal debate over whether Mr. Trump engaged in an insurrection obscured the extraordinary reality that he is running for president at all — returning with fresh vengeance and a familiar playbook built around the notions that he can never lose, will never be convicted and will never really go away.

That blueprint remains intact largely because his approach continues to yield political returns.

Far from agonizing over the collateral damage from his never-surrender ethos, Mr. Trump seems incentivized by strife, tightly braiding his legal defense with his presidential campaign. He has tried to run out the clock on his criminal trials, a strategy that earned a new victory on Friday when the Supreme Court declined to decide a key point of contention in his federal 2020 election case immediately.

While this year began with most Republicans telling pollsters that they preferred a different presidential nominee, the calendar will flip to 2024 with roughly two-thirds of the party aligned behind Mr. Trump. His legal problems, which in decades past would have bolstered rivals for a major party’s presidential nomination, have only caused Republican voters to unify around him more.