The inauguration will mark the climax of a weekend-long celebration -- and for African-Americans, a 200-year wait for the country to live up to its promise of equality for everyone, regardless of skin color.
Gov. Deval Patrick, the first black governor of Massachusetts, said his friend and president-elect has a tall order in his speech because the "excitement is absolutely palpable." Obama must also address the problems the nation faces, including a financial crisis, two wars and the looming threats from around the world.
"It will be very candid and very appropriate in the sense that he will strike a balance between the momentous nature of the occasion but also the huge challenges in front of us," Patrick said.
"I think he will strike tomorrow the perfect tone, because he will call upon the American people to answer the call of service, to answer the call to help reform government and to be accountable to the American people."
Obama will also be subject to high expectations. The politician known for wowing tens of thousands on the campaign trail will have his biggest audience ever Tuesday. And an ABC News/Washington Post poll put his favorability rating at 79 percent, the highest for an incoming president since Ronald Reagan.
The top aides around Obama are expected to begin work almost as soon as Obama stops speaking.
"I think that is very, very true," Stephanopoulos told "GMA " "They have an agenda set for the first 100 hours of the first 100 days where they want to demonstrate ... they'll hit the ground running."
He said to expect actions "in the first couple of days on issues like stem cell research. ... It means appointing new envoys to hot spots like Iran, Afghanistan and Pakistan to demonstrate a fresh start in foreign policy as well."
Obama, who has promised change in Washington, is trying to set a bipartisan tone right away. His inauguration celebration includes three dinners this evening to honor people who have reached across the aisle.
Two of those honorees are Republicans, including Sen. John McCain, R-Ariz., the man Obama defeated to become president.
ABC News' chief Washington correspondent George Stephanopoulos told "Good Morning America" the dinner for McCain is a "measure of the bridges they are trying to build. ... That is remarkable."
The other two dinners will salute former Secretary of State Gen. Colin Powell, a Republican, and Biden.
But first, the celebration. A constellation of stars serenaded the Obamas at the Lincoln Memorial Sunday. The lineup, dubbed "Obamastock," included Bono, Bruce Springsteen, Beyonce, and Usher. Comedian Jamie Foxx spoofed Obama by imitating the way he speaks.
Obama has invoked Lincoln repeatedly in the run-up to his swearing-in. He spent much of the weekend on a train retracing part of the route that Lincoln took to Washington for his own inauguration.
As Obama planned out his first steps, President Bush made some of his farewells. He called world leaders, including Russian Prime Minister Vladimir Putin and Italian Prime Minister Silvio Berlusconi, to say goodbye.
Bush plans to fly home to Texas on Air Force One after Obama's swearing-in and has invited about 10 friends to join him and wife Laura for the trip back home.