It’s a new race. Harris’ acceptance speech showed why.

CHICAGO — Donald Trump has dispensed with either mystery or nuance about the case he will make over the next 74 days against Kamala Harris.

The former president says the current vice president is leftist (“Comrade Kamala,” “far more liberal than crazy Bernie Sanders”). She is a lightweight (“stupid,” “dumb”). She is a phony, defined only by her ambition, disconnected from ordinary Americans (“So I don’t know, is she Indian or she is Black?” “What happened to her laugh?…That’s the laugh of a crazy person ”).

Over just 40 minutes Thursday night, Harris accepted the Democratic nomination with a fluent, forceful, tightly argued address that aimed to dismantle Trump’s caricature of her.

It is hard to imagine anyone who started watching the speech with an undecided but genuinely open mind — surely there are a few such people left in this agitated age? — who finished by thinking, You know, I see what Trump was getting about her.

Harris became the Democratic nominee only because of a spectacularly weak public performance by President Joe Biden less than two months ago at his debate with Trump. The format of an acceptance speech is quite different, obviously. Even so Harris’ performance was in every way the opposite.

Harris validated, and almost certainly fortified, the widespread perception left by recent national and swing-state polls that this is a transformed race. In the wake of the Democratic convention, Trump faces an urgent imperative to prevent Harris from delivering a similarly effective performance at their planned debate on Sept. 10.

Narrating her biography, Harris said her values ​​are shaped by her early career as a prosecutor. This background was also reflected in her rhetorical tone — well-organized, plain-spoken, largely concerned of lyrical flights.

On substance, however, it seemed apparent that Harris wasn’t simply prosecuting her case. The speech had a large and strategically important defensive dimension.

Rather than unveiling a markedly left-leaning agenda, Harris mostly presented a composite of priorities that unify most Democrats: Protecting abortion rights, voting rights, and Social Security and Medicare. Even within this familiar terrain, she often played notes that emphasized traditional and tough-minded. She boasted that as a prosecutor and attorney general, she confronted drug cartels as well as exploitative banks. She said she wants a middle-class tax cut, while asserting that Trump’s tax changes would provide relief to the rich at the expense of others.

On national security, Harris seemed at pains to put to rest any doubts that the country’s first woman president would be sufficiently tough. “As vice president, I have confronted threats to our security, negotiated with foreign leaders, strengthened our alliances and engaged with our brave troops overseas,” she said. “As commander in chief, I will ensure America always has the strongest, most lethal fighting force in the world.”

Knowing that Trump intends to make her own an immigration crisis, she tried to turn the tables. She blamed him for killing a bipartisan border security bill because he wanted a political issue rather than a policy solution, and vowed she would revive the measure and pass it.

Knowing that the Israel-Hamas war threatens to divide her party, Harris tried — depending on one’s perspective — to find a middle ground or blur the issue with language that offered something both sides could connect with. She was equally impassioned in saying “I will always stand up for Israel’s right to defend itself,” and in asserting that she is part of the Biden administration’s effort to see that “the suffering in Gaza ends and the Palestinian people can realize their right to dignity, security, freedom and self-determination.”

The most important part of Harris’ defensive agenda, however, was not about politics or policy but about herself personally. A woman with a biography that some voters may find exotic — a daughter of a mixed-race marriage, coming from a liberal city in a liberal state — told her story in ways to make herself approachable, familiar, reassuring.

There were paeans to a mother who “never lost her cool,” and taught her daughters to “never complain about injustice, but do something about it.” She described a close-knit community in the East Bay of California, “A beautiful, working-class neighborhood of firefighters, nurses and construction workers.” She described her patriotism: “Fellow Americans, I love our country with all my heart.”

There seemed to be a clear logic to Harris practicing the politics of reassurance. She and her team evidently believe that preempting attacks on her record or character is the necessary prerequisite to leveling her own attacks on Trump’s character and record.

She called Trump “an unserious man” but warned that the effects of a second term would be “extremely serious.” There was basically no item in Democrats’ standard anti-Trump litany that she did not mention: election denialism and the Jan. 6 riot, his recent 34-count felony conviction in New York, the civil suit he lost before that in a sexual harassment case, his skepticism of the NATO alliance and defending Ukraine from Russian attacks, his alleged sympathy for Vladimir Putin and Kim Jong Un in North Korea.

Earlier in her speech, Harris noted that as a government attorney, “for my entire career, I’ve only had one client: The people.” She returned to that later to note that, because of the rightward shift of the Supreme Court, Trump would face fewer checks in a second term than he did in the first: “Just imagine Donald Trump with no guardrails, and how he would use the immense powers of the presidency of the United States. Not to improve your life, not to strengthen our national security, but to serve the only client he has ever had: himself.”

A politician who can effectively meld offensive and defensive politics in one speech is a formidable threat. This gift was the essence of Bill Clinton’s and Barack Obama’s success. It was something that eluded Hillary Rodham Clinton at key moments in 2016. And it was something that Democrats concluded was impossible to imagine an aging Biden doing in 2024, despite his success in 2020.

There is little doubt after Harris’ speech that Trump and his campaign realize she has changed the trajectory of the campaign, nor that they are busy thinking of ways they can try to change it again.