FAIRFAX, Va. ― First lady Michelle Obama said her husband takes the high road when people question whether he was born in the United States.

When President Barack Obama was elected, “people had all kinds of questions about what kind of president Barack would be. Things like ‘Does he understand us?’ ‘Will he protect us?’” the first lady said during a rally at George Mason University, her first appearance on the campaign trail for Hillary Clinton. “There were those who questioned and continue to question for the past eight years, up through this very day, whether my husband was even born in this country.”

Echoing her speech at the Democratic National Convention, the first lady said that the president had responded to questions about his citizenship by refusing to stoop to the level of those questioning it.

“During his time in office, I think Barack has answered those questions with the example he’s set by going high when they go low,” she said. “And he’s answered these questions with the progress we’ve achieved together.”

She didn’t mention Donald Trump by name, but the comment was unmistakably a response to the Republican nominee, who built his political career around birtherism. On Friday, he falsely blamed the so-called birther movement on Hillary Clinton and said he had finished the movement. He also said he believed Obama was born in the U.S., though he has openly stoked birtherism even after the president released his long-form birth certificate in 2011.

President Obama showed just how he takes the high road on Friday. Asked about Trump’s birther comments by White House reporters, he said he hoped the presidential election would focus on more serious issues.

“I was pretty confident about where I was born,” he said. “I think most people were as well. And my hope would be that the presidential election reflects more serious issues than that.”