WASHINGTON -- Three days of inaugural celebrations kicked off in Washington Saturday, with President Barack Obama heading up a National Day of Service ahead of his swearing-in for a second term.

The president and first lady, Michelle Obama, planned to volunteer in the Washington area Saturday. Vice President Joe Biden, his wife, Jill, and others members of his family spent the morning filling care packages for U.S. troops serving overseas, veterans and first responders.

Obama added the day of service projects in 2009 and hopes it will become a tradition for future presidents.

Volunteers also gathered on the National Mall on a crisp, sunny morning in Washington for a service summit. In a videotaped message played at the event, Mrs. Obama said the volunteers were "showing once again that by giving back, we can lift up our fellow citizens and build stronger, healthier communities."

Former first daughter Chelsea Clinton, the honorary chairwoman of the volunteer effort, kicked off the summit by praising her family's "chain of service."

The president will be officially sworn in for his second term on Sunday in a small ceremony at the White House. He'll take the oath of office again on Monday before hundreds of thousands of people on the National Mall, followed by the traditional parade and formal balls.

Thousands of workers and volunteers were making final preparations for the celebration. Hotels and government buildings along the parade route were adorned with red, white and blue bunting. White tents, trailers and generators lined the Mall.

Yet there is decidedly less energy surrounding Obama's second inauguration than there was in 2009. That history-making event drew 1.8 million people for the swearing-in of the nation's first black president.

This time, Obama takes the oath of office following a bruising presidential campaign and four years of partisan fighting. He's more experienced in the ways of Washington. He has the gray hair and lower approval ratings to show for it.

For at least the inauguration weekend, the fiscal fights and legislative wrangling will be put aside in favor of pomp and circumstance.

The White House did not say in advance what Obama's service project would be. In 2009, he helped spruce up a shelter for homeless teens in one of Washington's poorer neighborhoods then visited wounded soldiers at Walter Reed Army Medical Center.

The White House sees the call to service as a way for Americans across the country to honor the memory of Martin Luther King Jr. The day Obama publicly takes the oath of office marks King's birthday, and 2013 is the 50th anniversary of the civil rights leader's March on Washington.

Also Saturday, Michelle Obama and Jill Biden were hosting the Kids' Inaugural Concert, an evening event paying special tribute to military spouses and children.

The crowds pouring into Washington were expected to be far smaller than they were four years ago, and there will be fewer inaugural balls for the president and first lady to attend. Still, Obama's swearing-in at the Capitol is expected to draw up to 800,000 people, which would make it the largest second.

The president was still working on his inaugural address heading into the weekend. He isn't expected to delve deeply into the policy objectives he'll tackle in a second term, but the tone and theme of the speech will set the stage for the policy fights to come.

Aides said he will make the point that while the nation's political system doesn't require politicians to resolve all of their differences, it does require Washington to act on issues where there is common ground. He will speak about how the nation's core principles can still guide a country that has changed immensely since its founding.

Temperatures were forecast to fall throughout the weekend and be in the 30s on Monday when the crowds gather along the parade route that will take Obama from Capitol Hill to the White House.

Despite scaling back on some of the revelry, the inauguration will be a star-studded affair. Top acts including Beyonce, Katy Perry and Brad Paisley have signed on to perform at the weekend's events.

The inauguration also is bringing thousands of Obama campaign staffers and donors to Washington, with many getting invitations for tours and other events at the White House. On Friday, the president and first lady held two private events for donors who helped finance his 2012 campaign.