President elect Barack Obama stops for a visit while participating in a renovation project at Sasha Bruce Youthwork, a shelter for homeless or runaway teens, in Washington.

Washington ? On the eve of his inauguration, President-elect Barack Obama visited wounded troops at a military hospital, helped paint a wall at a shelter for homeless teens and paid tribute to the Rev. Martin Luther King Jr. on the civil rights leader’s national day. He said there can’t be “idle hands” at a time of national hardship and pledged to make the government do its part.

Invoking King’s legacy as “not just a dreamer, but a doer,” Obama urged all Americans to pitch in and take part in community service.

Ever-growing crowds thronged to the capital city on the eve of Obama’s elevation to the presidency. “Tomorrow, we will come together as one people on the same Mall where Dr. King’s dream echoes still,” Obama said.

At lunchtime, Michelle Obama joined her husband at Calvin Coolidge High School, where the couple greeted 300 people who were writing letters to U.S. troops and doing other volunteer activities. Obama thanked them for following King’s path of service.

“If we’re waiting for somebody else to do something, it never gets done,” said Obama, once a community organizer in Chicago. “We’re going to have to take responsibility, all of us. This is not just a one-day affair.”

As for himself, Obama said, “I am making a commitment to you as your next president that we are going to make government work.”

On the National Mall, a party atmosphere was already evident by midday as snow fell lightly. Several of the large-screen televisions were reshowing Sunday’s concert, while in a corner near the Smithsonian Air and Space Museum, the Boy’s Choir of Kenya performed an impromptu selection for the crowd.

At the Capitol, hundreds of people pressed up against the blocked-off seating area in hopes of getting as close to the inaugural stage as possible.

“Everybody’s excited,” said Donald Butler, 20, a student at the University of Washington. “There are smiling faces everywhere, and it’s a nice, diverse crowd. It’s history. I didn’t think I would see a black president in my generation. I just had to be here.” Butler is black.

A day away from becoming the nation’s 44th president, Obama made a morning visit to 14 injured vets from Iraq and Afghanistan at Walter Reed Army Medical Center.

Then he visited Sasha Bruce House, a shelter for homeless teens, chatting with volunteers who were helping to repaint rooms and then joining in himself.

“We can’t allow any idle hands. Everybody’s got to be involved. I think the American people are ready to do that,” Obama said, grabbing a paint roller to help give the walls a fresh coat of blue. “I think I’ve got this wall covered,” he said.

Obama, whose presidential campaign made extensive use of the Internet to rally support and gather contributions, said, “We don’t want to just use it for winning elections, we want to use it for rebuilding America.” He said thousands of people were volunteering on Monday, partly organized by online appeals.

Obama also said he spoke with the pilot who safely landed a disabled airliner in the Hudson River, US Airways Capt. Chesley B. “Sully” Sullenberger.

“He said, ‘Me and my crew, we were just doing our job.’ And it made me think, if everybody did their job — whatever that job was — as well as that pilot did his job, we’d be in pretty good shape,” Obama said. Sullenberger, his crew and family were invited by Obama to attend Tuesday’s inauguration.

Michelle Obama and Vice President-elect Joe Biden’s wife, Jill, visited RFK Stadium where people were at work wrapping care packages and writing letters to troops overseas.

Massachusetts Gov. Deval Patrick, one of those helping out with the care packages, said, “There’s a tremendous spirit in Washington.”

President George W. Bush, with just a day left in his term, made phone calls from the White House to Russian Prime Minister Vladimir Putin and a dozen other world leaders to thank them for their work with him over the past eight years.

In his final acts of clemency, Bush commuted the prison sentences of two former U.S. Border Patrol agents whose convictions for shooting a Mexican drug dealer ignited fierce debate about illegal immigration.

Defense Secretary Robert Gates, meanwhile, was designated by the Bush administration to stay away from Tuesday’s inaugural festivities “in order to ensure continuity of government,” said Bush spokeswoman Dana Perino. One official traditionally stays away when others in the line of presidential succession are gathered together, in case of a calamitous attack.

On the streets, live news broadcasts displayed on large-screen televisions attracted swarms of onlookers, and behind the scenes people made final preparations for a slew of parties, balls and other celebrations that will follow Obama’s oath-taking and the inaugural parade.

Obama and Biden, fresh off a rollicking concert at the Lincoln Memorial on Sunday, were spending their final day before the inauguration with activities keyed to the celebration of King’s life, cut short by an assassin’s bullet in 1968.

“Today, we celebrate the life of a preacher who, more than 45 years ago, stood on our National Mall in the shadow of Lincoln and shared his dream for our nation. His was a vision that all Americans might share the freedom to make of our lives what we will; that our children might climb higher than we would,” Obama said in a statement.

Obama said King’s “was a life lived in loving service to others.”

Meanwhile, two wreaths were erected at the future site of the Dr. Martin Luther King Jr. Memorial on the Tidal Basin between the Jefferson Memorial and the Lincoln Memorial. Groups of school children gathered around retired teacher Kirk Moses as he talked about King’s legacy of nonviolence and the civil rights leader’s connection to Obama.

“The cadence and syntax of Obama, it comes directly from Dr. King,” said Moses, 60, as his group took pictures of the bronze plaque that sits where the memorial will be built.

The run-up to Obama’s inauguration, like his election itself, has been defined by enormous public enthusiasm, carefully choreographed events and a lofty spirit of unity. What awaits, as Obama often reminds the nation, is many months, if not years, of tough work.

The celebrations began Saturday with Obama’s whistle-stop tour, from Philadelphia to Washington, along the path Abraham Lincoln took in 1861. Then came the roaring celebrity-filled concert where several hundred thousand people flanked the Reflecting Pool, hearing actors, singers and then Obama himself rally for national renewal.

The Presidential Inaugural Committee has launched a Web site, USAService.org, to help people find volunteer opportunities close to their homes.