Joe Biden called for unity and bipartisan cooperation as he claimed victory on Saturday night, and said it was time to end a “grim era of demonization.”

“This is the time to heal in America,” Biden said in front of a cheering crowd of supporters at a drive-in rally at the Chase Center in Wilmington, Del.

Biden will be sworn in in January as the 46th president of the United States. He nodded to the likelihood that he will face a Republican-controlled Senate, saying it was time for political leaders to begin to cooperate again.

“The refusal of Democrats and Republicans to cooperate with one another is not some mysterious force beyond our control,” he said. “It’s a decision. It’s a choice we make. And if we can decide not to cooperate, then we can decide to cooperate. And I believe that this is part of the mandate from the American people. They want us to cooperate.”

Biden was introduced by Vice President-elect Kamala Harris, who will become the first woman, first African American and first Asian American to hold that office. Both nodded to that history-making moment.

“I may be the first woman in this office, but I will not be the last,” Harris said, to enthusiastic honking from the crowd. “Because every little girl watching tonight sees that this is a country of possibilities.”

Biden also took note of that breakthrough, saying “It’s long overdue.” He also said that his administration would reflect America.

Biden reached out to Trump supporters. “And to those who voted for President Trump, I understand your disappointment tonight,” he said. “I’ve lost a couple of elections myself. But now, let’s give each other a chance.”

Biden and Harris were declared the winners around 11:30 a.m. on Saturday, after four days of ballot counting in a handful of swing states. Trump has refused to concede thus far, and continues to pursue legal challenges in several states.

Biden said he would appoint a team of scientific advisers to consult during the transition on the coronavirus.

“Our work begins with getting COVID under control,” he said. “I will spare no effort — or commitment — to turn this pandemic around.”

Harris wore a white suit, just as Hillary Clinton had done at key moments of her 2016 campaign in a nod to the suffrage movement. Geraldine Ferraro, the first woman nominated for vice president, also wore a white suit at her Democratic convention speech in 1984.

Harris paid tribute to her late mother, Shyamala Gopalan Harris, and to Black women, “who are too often overlooked, but so often prove that they are the backbone of our democracy.” She also thanked generations of women of all races who had worked in the suffrage movement, the Civil Rights movement, and in today’s struggles for voting rights.

“I stand on their shoulders,” she said.