WASHINGTON — With the Democratic primary behind her, Hillary Clinton said she now plans to put Republican Donald Trump’s economic record and agenda at the center of her campaign, calling his ideas “deeply misguided” and “dangerously incoherent.”

In an interview Wednesday, Clinton said she would deliver an economic speech soon contrasting Trump’s record and policies with her own, modeled after a foreign-policy speech she gave last week. In that speech, she offered a robust and often biting critique of the presumptive Republican nominee’s stances on global affairs, charging he was “temperamentally unfit” to serve as commander-in-chief.

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Trump is hardly shrinking from the fight. He promised Tuesday night to deliver a “major speech” as early as Monday laying out the case for how Clinton and her husband, former President Bill Clinton, have perfected what he called the “politics of personal enrichment.”

With the general election now effectively under way, the exchanges left no doubt that the next five months will be particularly bitter and divisive as both candidates strive to patch up divisions within their own parties while asserting the other shouldn’t be president.

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For her own part, Clinton promised in the interview to put forth a middle-class tax-cut plan, which she said would be a “critical” part of the case she makes to voters. She wouldn’t say whether she supports bipartisan efforts to overhaul the corporate tax code by lowering rates and eliminating some tax breaks, but she promised more details in the weeks ahead.

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The interview came a day after the former first lady, senator and secretary of state made history as the first woman to capture the nomination of a major political party. She plans to travel to Ohio and Pennsylvania next week, two states where some analysts have predicted that Trump’s brand of economic populism will resonate, particularly with white, working-class men.

Clinton said she was also working to unify Democrats. She spoke to rival Bernie Sanders on Tuesday evening and said she would continue making the case to his supporters that there is more that unites than divides them.

An expanded version of this report appears on WSJ.com.