Breaking News:Michelle Obama, Thrashing Trump, Suggests the Presidency Is a ‘Black Job’… See More Details

The former first lady enthralled a packed arena on Tuesday evening with one of the Democratic National Convention’s most emphatic takedowns of Donald J. Trump.

Michelle Obama, the former first lady and one of the most popular figures in the Democratic Party, delivered one of the Democratic National Convention’s most emphatic takedowns of former President Donald J. Trump on Tuesday night and turned one of his most controversial campaign lines against him: “Who’s going to tell him that the job he’s currently seeking might just be one of those ‘Black jobs’?” she said.

Mrs. Obama, a reluctant campaigner, enthralled a packed arena in Chicago with a convention appearance that lent firepower to Vice President Kamala Harris’s presidential campaign. She offered support and praise for Ms. Harris, but focused much of her nearly 20-minute speech squarely on Mr. Trump, mocking his past comments, his background and his behavior, while mostly avoiding naming him.

And for a speech delivered at a political convention, her remarks struck a remarkably personal tone as she spoke of the former president, who led a multiyear campaign to question the birthplace of her husband, former President Barack Obama.

“For years, Donald Trump did everything in his power to try to make people fear us,” she said, adding that “his limited, narrow view of the world made him feel threatened by the existence of two hardworking, highly educated, successful people who happen to be Black.”

She zeroed in on his debate-night complaint about immigrants taking “Black jobs” by pointing out that the presidency of the United States has been one and might soon be again. She said that Americans like Ms. Harris understood “that most of us will never be afforded the grace of failing forward,” a reference to Mr. Trump’s business troubles. She noted that most Americans do not grow up with “the affirmative action of generational wealth.” (Mr. Trump was born into a wealthy family in Queens.)

“If we see a mountain in front of us, we don’t expect there to be an escalator waiting to take us to the top,” she said. Line by line, she received thunderous applause.

Mrs. Obama’s speech, delivered with a clear voice as she looked straight into the camera to address Americans watching at home, was not saccharine. She began her time onstage by framing her remarks in the context of reaching for hope through despair.

She gave a tribute to her mother, Marian Robinson, who died in May. Mrs. Obama said that she had not been sure she would be stable enough to take the stage on Tuesday night. When the Obamas took office in 2009, her mother left Chicago and moved into the White House to help raise Sasha and Malia Obama.

“The last time I was here in my hometown was to memorialize my mother, the woman who showed me the meaning of hard work and humility and decency, the woman who set my moral compass high and showed me the power of my own voice,” Mrs. Obama said.