“We have never gone wrong when we expanded rights and responsibilities to everybody,” the president said to cheers from the audience. “That doesn’t weaken families, that strengthens families. It’s the right thing to do.”

His comments came after presumptive Republican nominee Mitt Romney told graduating students at Liberty University, a school founded by the late conservative televangelist Jerry Falwell, that marriage is between “one man and one woman.”

“The good news is, I think the American people are on our side on this,” Obama said at the New York event. Polls show that Americans are deeply divided on gay marriage. Younger Americans — a key part of the president’s history-making 2008 coalition — tend to be more supportive.