Donald Trump has long been a man undone by himself.

He imperiled his presidency and political campaigns with personal grudges, impulsiveness and an appetite for authoritarianism. His casual approach to the rule of law — and unwillingness to accept electoral defeat — resulted in $83 million in penalties, nearly three dozen felony convictions and additional legal trouble ahead.

But Thursday night, with his right ear still bandaged five days after he was wounded by a would-be assassin’s bullet, Trump attempted a politically cunning transformation.

He opened his address by casting himself as a unifying figure, promising to bridge political divides he had long delighted in deepening. He mentioned President Joe Biden by name only once. At brief moments, he struck tones more similar to President Barack Obama’s message of hope and healing than to the dark version of America that Trump described in accepting his first two Republican presidential nominations.

“The discord and division in our society must be healed — we must heal it quickly,” Trump said on the Republican convention’s final night. “As Americans, we are bound together by a single fate and a shared destiny. We rise together — or we fall apart.”

With the Democrats divided and polls tipping in Trump’s favor, Republicans used their national gathering in Milwaukee to bask in the moment. In their view, Trump — twice impeached, repeatedly indicted, convicted, fined and soon to be sentenced — appears on the verge of regaining control of the world’s most powerful office.

Yet even this speech, designed to debut the new message, underscored Trump’s challenge with discipline. He stuck to the script at the start. But as the clock ticked well beyond the one-hour mark, he couldn’t resist falling back into the kind of rambling, unscripted diatribe that has long been his signature style. At more than 90 minutes, it was the longest Republican nomination speech since at least 1956, when the American Presidency Project at the University of California, Santa Barbara, started tracking the statistic on the GOP side.

Trump’s ultimate success will depend on whether, for the final 15 weeks of the campaign, he can contain his self-destructive tendencies and temper his preference for vengeance and unpopular, hard-right policies. Since voters rejected him at the ballot box in 2020, Trump has embraced an increasingly unrestrained and radical version of conservatism that has often bordered on authoritarian.

Last March, he framed his campaign as the “final battle” against his political opponents and told supporters, “I am your retribution.” In October, he declared that immigrants were “poisoning the blood” of the country. A month later, on Veterans Day, he degraded adversaries as “vermin” who needed to be “rooted out.” In December, he said he’d be a dictator — but only on his first day back in office. Last month, Trump promised to appoint a special prosecutor to target Biden and his family.

For a night at least, such open threats and nakedly vicious imagery were largely absent from his address. Still, in a speech designed to place a friendlier face on Trumpism, the former president couldn’t resist a handful of exaggerations and personal attacks.

He derided former House Speaker Nancy Pelosi as “Crazy Nancy.” Less than four years removed from office, he said America was already a “nation in decline.” He waxed hyperbolic about the immigration crisis, calling it “the greatest invasion in history” and compared migrants who entered the country illegally to Hannibal Lecter, the fictional serial killer and cannibal from “The Silence of the Lambs.”

“In fact, I am the one saving democracy for the people of our country,” Trump said, ignoring his role in setting off the Jan. 6, 2021, riot by his supporters on the Capitol.

“I am running to be president for all of America, not half of America, because there is no victory in winning for half of America,” Trump said.

According to close allies of Trump, much of the former president’s newfound temperance was a result of a near-death experience at his campaign rally last Saturday.

On the stage Thursday, Trump recounted the story of his shooting, telling the crowd that “you’ll never hear it from me a second time, because it’s actually too painful to tell.” He seemed touched by the devotion of his supporters, describing the shooting as almost a spiritual experience — even “providential.”

“Bullets were flying over us, yet I felt serene,” he said. “I stand before you in this arena only by the grace of almighty God.”

If it endures beyond the convention, Trump’s new approach poses fresh challenges for Democrats. For eight years, Trump has been their most potent political weapon, a way to rally their base against a leader they reviled even more than they loved the leaders of their own party.

They have tried to transform this race into yet another referendum on Trump, rather than the question of whether Biden remains fit for a second term. Already, Biden aides say they’ve struggled to combat what some call “Trump amnesia,” a sense that many Americans have forgotten how much they disliked the chaos and division of the Trump years.