Transcript for Joseph R. Biden, Kamala Harris sworn in
Good evening on this historic night in America. Something we witness as a nation together ever four years. A peaceful trarnser if of power. But we all know that notion was tested in recent weeks, but today, America's new president, Joe Biden, saying democracy has prevailed. Saying, "Iwill be a president for all Americans," calling for unity. The President-Elect Joe Biden shortly before noon taking the oath of office as America's 46th president, entering office amid multiple crises at once. First running for president 30 years ago. His hard work, empathy bringing him to this moment. The Bidens 'em brising after the swearing in, using the Biden family bible, in the family for more than 100 years. Vice President-Elect kamala Harris was sworn in just before him as the first woman vice president, the first black, the first asian-american vp. The daughter of immigrants, of Blac and Indian heritage. She is now the highest ranking wool in American history. Sharing this moment with former president Barack Obama as he now witnesses history made by her today. Former president Obama tweeting today to the new president, "Congratulations to my friend, this is your time." P vice president Mike pence there for the inauguration. President trump skipping it. Vice president Harris escorting former vice president pence down the steps of the capitol. Former president trump and the former first lady leaving the white house early this morning. One last trip on air force one for Florida. His message to supporters and to the incoming administration in a moment. Late this afternoon, the first family arriving at the white house and the first lady putting her head on the president's chest before heading inside the white house. Tonight here, president Joe Biden already at work. The executive actions already and we're going to guide you through it all. And we begin with ABC's chief white house correspondent Cecilia Vega leading us off. Reporter: Today, Joe Biden's nearly 50-year political career led him up the steps of the capitol, through its halls and into history. Sworn in at an extraordinary time, the nation's enormous challenges laid bare right in front of him. There was no huge crowd. The audience socially distanced, a mask on every face. But three of Biden's predecessors were onhand. The Clintons, the bushes and the Obamas. Former president Obama, exchanging fist bumps with kamala Harris, who was about to make so much history of her own as the first woman, the first black American and first person of southeast Asian decent to be vice president. The vice president of the United States, the honorable Michael R. Pence and Mrs. Karen Reporter: The man she would replace, Mike pence, there, too. Though former president trump was not. The capitol, still bearing scars of what happened there just two weeks ago. Today, a special honor given to one capitol police officer who tried to fend off the the United States capitol police officer private first class Eugene O. Goodman. Reporter: But this was a day for celebration, complete with lady gaga. O say can you see by the dawn's early light Reporter: Harris, first to take the oath, making her the highest ranking elected woman in American history, sworn in by another first, justice Sonia Sotomayor, the first Latina on the supreme court. I, kamala devi Harris, do solemnly swear. Reporter: And then, the moment Joe Biden has wanted his entire life. His hand on the bible that has been in his family for more than 100 years. I, Joseph Robinette Biden Jr., do solemnly swear. That I will faithfully execute. That I will faithfully execute. The office of president of the United States. The office of president of the United States. And will to the best of my ability. And will to the best of my ability. Preserve, protect and defend. Preserve, protect and defend. The constitution of the United States. The constitution of the United States. So help you god. So help me god. Congratulations, Mr. President. Reporter: A kiss for the emotional new first lady. Then, president Biden got to work, setting out to heal this nation after the hard-fought election and its bitter aftermath. This is America's day. This is democracy's day, a day of history and hope, of renewal and resolve. We've learned again that democracy is precious. Democracy is fragile. And at this hour, my friends, democracy has prevailed. Reporter: Still, the new president calling this a time of testing. We face an attack on our democracy and on truth. A raging virus, growing inequity, the sting of systemic racism, a climate in crisis. America's role in the world. To overcome these challenges, to restore the soul and secure the future of America, requires so much more than words. It requires the most elusive of all things in a democracy, unity. Unity. Reporter: He demanded an end to what he called an "Uncivil war pitting red against blue, rural versus urban, conservative versus liberal." He did not mention Donald Trump, but he did extend an olive branch to the millions of Americans who voted for him. To all of those who did not support us, let me say this -- hear me out as we move forward. Take a measure of me and my heart. Yet hear me clearly. Disagreement must not lead to disunion. And I pledge this to you, I will be a president for all Americans. All Americans. And I promise you, I will fight as hard for those who did not support me as for those who did. Reporter: Biden warning these divisions can not stand as we enter what may be the deadliest period of this pandemic. We must set aside politics and finally face this pandemic as one nation. One nation. We will get through this together. Together. Reporter: In his first act as president, Biden asking for a moment of silence to remember the 400,000 Americans killed. Let's say a silent prayer for those who have lost their lives and those left behind and for our country. Reporter: Biden then making this promise to the nation he now leads. I give you my word, I will always level with you. I will defend the constitution. I'll defend our democracy. I'll defend America. And together, we shall write an American story of hope, not fear. Of unity, not division. Of light, not darkness. And a story that tells ages yet to come that we's the call of history. President Biden on the steps of the capitol today. Let's get right to Cecilia Vega at the white house tonight. Cecilia, I want to go back to that image we showed at the top tonight, president Biden, the first lady, her head on his chest as they arrived at the white house. The weight of the moment catching up to them. And Cecilia, you learned that when the new president entered the oval office today, there was a letter waiting for former president trump? He skipped the inauguration, but he kept that one tradition of leaving a letter? Reporter: Yeah, and it was a big question, David, leading into today, because as you know, the president has extended so few of the niceties usually offered by a president to his successor. But yes, this letter was on the resolute desk, we're told, it surprised people in president trump's orbit. They weren't sure if he would do it. But president Biden now in the oval office behind me, speaking to reporters just a short time ago, said that the letter was there but it was private, he didn't want to tell us what was in it but he said it was a very generous letter and he wanted to speak to president trump before he released the results of it. Generous was the word he used. Cecilia, thank you. President Biden, meanwhile, already at work tonight.
This transcript has been automatically generated and may not be 100% accurate.