Steve Kerr, the coach of the Golden State Warriors, praised Vice President Kamala Harris onstage on Monday night and urged Americans to come together to reject former President Donald J. Trump as if they were one united basketball team.

“Think about what our team achieved with 12 Americans in Paris, putting aside rivalries to represent our country,” Mr. Kerr said at the Democratic convention in Chicago, referring to the Olympic gold medal he won this month as the coach for the U.S. team. “Now imagine what we could do with all 330 million of us playing on the same team.”

Mr. Kerr, one of the most outspoken liberal voices in American sports, employed the high-minded language that Bay Area sports fans have come to expect from him when he opines on pressing issues of the day, especially gun violence.

“Leadership, real leadership,” Mr. Kerr said, is “not the kind that seeks to divide us, but the kind that recognizes and celebrates our common purpose.”

But he also wove in plenty of sports references, speaking in an arena where he won three N.B.A. championships as a member of the Michael Jordan-led Chicago Bulls.

“Coach to coach, that guy’s awesome,” Mr. Kerr said of Gov. Tim Walz of Minnesota, Ms. Harris’s running mate and a former high school football coach. But, he joked, Mr. Walz’s defensive coaching left a little to be desired. “Way too much reliance on the blitz, in 1999, against Mankato East,” Mr. Kerr said.

Mr. Kerr’s appearance was meant to give Democrats a bigger conduit into the enormously influential sports world. Some prominent sports media personalities and athletes, like Stephen A. Smith, the ESPN commentator, and Aaron Rodgers, the New York Jets quarterback, have embraced more libertarian or traditionally conservative views, and the sports talk world tends to skew conservative.

But the N.B.A. is an exception, and Mr. Kerr has stood out. He has criticized former President Donald J. Trump and been the subject of his ire; Mr. Trump mocked Mr. Kerr for sidestepping a question about democracy in Hong Kong in 2019.

Above all, Mr. Kerr has been a vocal advocate for gun control. Mr. Kerr’s father, Malcolm H. Kerr, was assassinated in Lebanon in 1983 by members of a militant group while serving as the president of the American University of Beirut during the country’s civil war, when the younger Mr. Kerr was 18 years old. The tragedy, Mr. Kerr has said, shaped his perspective on the world as he grew up, and he has invoked it occasionally when he has made impassioned calls to end gun violence.

After a gunman killed 19 children and two adults at an elementary school in Uvalde, Texas, in 2022, Mr. Kerr delivered an emotional message at a news conference before an N.B.A. playoff game.

“I’m fed up, I’ve had enough,” he said. “We’re going to play the game tonight. But I want every person here, every person listening to this, to think about your own child or grandchild, mother or father, sister, brother. How would you feel if this happened to you today?”

While in the United Arab Emirates last month with the U.S. basketball team as it prepared for the Olympics, Mr. Kerr said the assassination attempt against Mr. Trump was a “demoralizing day for our country.”

“It’s yet another example of not only our political division, but also gun culture,” he added.

Other leading N.B.A. figures have also been vocal proponents of liberal causes. Gregg Popovich, the longtime coach of the San Antonio Spurs known for his caustic comments, has frequently criticized Mr. Trump, assailing him as a “deranged idiot.”

In 2020 — two years after the Fox News commentator Laura Ingraham infamously told LeBron James to “shut up and dribble,” rather than engage in political activism — Mr. James and other players campaigned for Joseph R. Biden Jr. and successfully pushed the N.B.A. to turn arenas into polling places for the election.

So far, there has been less evidence of political campaigning from N.B.A. players this year, though Ms. Harris did meet with members of the U.S. team last month while they were preparing for the Paris Olympics at a training camp in Las Vegas. On the other side of the aisle, Royce White, a former N.B.A. player, won the Republican nomination for the Senate in Minnesota this month.

Mr. Kerr ended his remarks with a dig at Mr. Trump, referring to the signature move of his star player, Stephen Curry, who often celebrates an improbable three-point shot by placing his hands together against his head as if he is saying good night.

“After the results are tallied” on Election Day, Mr. Kerr said, “in the words of the great Steph Curry, we can tell Donald Trump, ‘Night, night!’”