President-elect Barack Obama will observe the Martin Luther King holiday by working on a volunteer service project. And he will attend three tribute dinners.

The president-elect, Michelle Obama, Vice-President-elect Joe Biden and Biden's wife Jill all plan to join service projects today, making the day set aside to remember the slain civil rights leader a day on, rather than a day off.

Later, Obama will make appearances at dinners honoring Biden, former Secretary of State Colin Powell and John McCain, the man he defeated last November.

At yesterday's Lincoln Memorial gala, Obama said America's problems are so grave it needs all its people's hands turned to the wheel. The vast crowd heard Obama say there is no obstacle that can stand in the way of millions of voices calling for change.