Biden, kicking off a coast-to-coast tour, is looking to lend his support to Democratic candidates and prevent Republicans taking control of Congress by touting the sharp differences between the major US parties.
"It's not hyperbole now you need to vote to literally save democracy again," Biden told an above-capacity crowd of several thousand at a Democratic National Committee event at Richard Montgomery High School in a Maryland suburb of Washington on Thursday.
"America must choose. You must choose. Whether our country will move forward or backward.
"Trump and the extreme MAGA Republicans have made their choice: to go backwards full of anger, violence, hate and division," he said, while Democrats have chosen to be a nation of unity and hope.
The event was promoted by groups including women's health provider Planned Parenthood and anti-gun violence activists Moms Demand, as Democrats lean on a new gun safety law and Republican-backed abortion bans to improve their midterm prospects.
Maryland's Montgomery County voted more than 78 per cent for Biden and Vice-President Kamala Harris in 2020.
Before the rally, Biden met Democratic donors at a party fundraiser north of Washington.
Strolling with a handheld mic, Biden detailed the tumult facing the United States and the world from climate change, and he spoke about economic upheaval and the future of China and was strongly critical of the direction of the Republican Party.
"We're seeing now either the beginning or the death knell of an extreme MAGA agenda," Biden said, referring to former president Donald Trump's "Make America Great Again" slogan.
"It's not just Trump ... It's almost semi-fascism."
Republicans hope to ride voter discontent with inflation to victory in November, and they have history on their side.
The party that controls the White House usually loses seats in Congress in a new president's first midterm elections, and political analysts predict Republicans have a solid chance of taking control of the House of Representatives and possibly the Senate.
Democrats hold a thin majority in the House, while the Senate is evenly divided, with the vice-president's tie-breaking power giving Democrats control.
