"I hope you know how grateful I am to all of you," Biden said.
Democrats kicked off their convention Monday with a who's who of guests who all touted Vice President Kamala Harris' run for the White House.
Several topics came up during the night including the future of reproductive rights and Project 2025.
Harris made a surprise appearance after several Democratic VIPS took the stage, including Rep. Alexandria Ocasio-Cortez.
The main stars of the night were some of the Democrats' longstanding figures including Secretary of State Hillary Clinton.
But the main spotlight came as President Joe Biden spoke to the cheering crowd, reflecting on his four years as president and his decision to "pass the torch" to Harris.
Four people were arrested after several protesters broke through an outer security fence outside the United Center during the pro-Palestinian rally "March on the DNC," police said.
There is a heavy police presence outside the venue, where the DNC will soon kick off.
The inner perimeter fence was not breached, police said.
President Joe Biden posted a video on social media touting his accomplishments and prominently features Vice President Kamala Harris just ahead of his speech at the DNC on Monday evening.
"Thank you, America, for keeping the faith," Biden wrote in a post on X.
Throughout the video, images of Harris flash on the screen, including of her meeting with Parkland shooting victims' parents, meeting with world leaders and sharing a moment with Justice Ketanji Brown Jackson.
-ABC News' Fritz Farrow, Gabriella Abdul-Hakim and Will McDuffie
Greetings from the Windy City -- or, as Chicago should be called, the City of Conventions. Chicago has hosted more political conventions than any other city in America. Before the 26th major-party political convention in Chicago history kicks off, watch this video my colleagues and I made this morning to familiarize yourself with the history of the other 25.
Greetings from the 2024 DNC in Chicago
-538's Nathaniel Rakich
Rep. Tom Suozzi, a moderate Democrat who flipped a New York district held by ousted Rep. George Santos, campaigned heavily on immigration and messaging that the Democrats should be tougher on the issue.
But Suozzi told ABC News on Monday he's happy with how Vice President Kamala Harris has handled the key 2024 issue so far.
"She came out early in this campaign and continues to talk about how she would have supported the bipartisan Senate deal to secure the border. Now, I think we're going to hear more and more details about securing the border, fixing the asylum system and helping those people that have been here for decades, that have played by the rules to try and lift them up," Suozzi said.
When asked if he's spoken with Harris since she began her presidential bid, Suozzi said he has not but has spoken with her team. Suozzi is also set to speak at the convention this week.
On the ticket as a whole, Suozzi told ABC News: "I feel great. I'm so excited about this ticket. I'm excited by the enthusiasm I see from the voters, not only in my district, but throughout the country."
-ABC News' Oren Oppenheim
