She began her speech with a message about faith and family: Her librarian mother and father, a shipyard worker, both became United Methodist ministers. The family had only one car, Ms. Abrams said, “so sometimes my dad had to hitchhike and walk long stretches during the 30-mile trip home from the shipyards.” One rainy night, she said, he gave away his jacket to a homeless man.

It was an anecdote meant to showcase Democrats’ concern for working people — a theme that House Democrats have hammered home with their so-called For the People agenda of lowering prescription drug prices, passing an infrastructure measure and ending corruption in Washington. Ms. Abrams hit hard on those themes throughout her address.

“In Georgia and around the country, people are striving for a middle class where a salary truly equals economic security,” she said. “But instead, families’ hopes are being crushed by Republican leadership that ignores real life or just doesn’t understand it. Under the current administration, far too many hard-working Americans are falling behind, living paycheck to paycheck, most without labor unions to protect them from even worse harm.”

She also attacked Mr. Trump over his immigration policies.

“We know bipartisanship could craft a 21st-century immigration plan, but this administration chooses to cage children and tear families apart,” Ms. Abrams said. “Compassionate treatment at the border is not the same as open borders.”

Ms. Abrams was not the only one to counter Mr. Trump. Two presidential hopefuls — Senators Bernie Sanders, independent of Vermont (who has not yet announced his candidacy but is widely expected to), and Kamala Harris, Democrat of California — delivered their own responses.

Ms. Harris, a former prosecutor who in 2017 became the second black woman to serve in the Senate (after Carol Moseley Braun of Illinois) delivered an eight-minute address, livestreamed on her Facebook page before Mr. Trump took the rostrum in the House chamber. She took the president to task for policies that she said benefit the rich and powerful, and outlined her own vision for a politics of unity rather than division.

“At this difficult moment we can have faith that the American people are spirited, resourceful and resilient,” Ms. Harris said, “and because of who we are we can come together around that common purpose.”