President Bush challenged the nation Monday to rekindle the volunteer spirit it had after the worst terrorist attacks in U.S. history, when people rushed to help others however they could.

"The truth of the matter is, the farther we've gotten away from 9/11, that memory has begun to fade," Bush told an audience of volunteers on the South Lawn.

"And some are saying, 'Well maybe I don't need to volunteer. Maybe the crisis has passed.' The aftermath of 9/11 isn't nearly as intense as it was," Bush said. "My call to people is, there's always a need. You should be volunteering not because of 9/11; you should be volunteering because our country needs you."

Bush spent most of his comments praising the strength of volunteerism around the country. But his call to service, coming on the week of the seventh anniversary of the Sept. 11 terrorist attacks, underscored worries that volunteering can tend to drop off after big tragedies.

The White House event also gave Bush a platform to tout what aides say is a little-known part of his legacy.

In 2002, Bush created USA Freedom Corps, a program that helps connect people to volunteer opportunities. It also helps bolster the many national service programs that existed before he took office. Since then, the White House says, the number of volunteers has jumped by more than 1 million people.

Bush's support for a variety of volunteer efforts is a message the White House wants to get out — particularly in the context of the Sept. 11 attacks.

Just one day earlier, the presidential candidate from Bush's own party, Sen. John McCain, essentially pointed blame at Bush on the very topic.

"I think one of the biggest mistakes that we ever made after 9/11, we told Americans, go shopping or take a trip," McCain said. "We should have said, OK, you're going to be part of a large group of Americans, the majority of Americans who are going to serve the country. And we're going to find ways for you to serve."

It appeared to be an allusion to an oft-mentioned speech Bush gave in Chicago about two weeks after the terrorist attacks, when the president told the public: "Get on board. Do your business around the country. Fly and enjoy America's great destination spots. Get down to Disney World in Florida."

The White House says Bush talked a lot at the time about the need for volunteerism, not just commerce. In his 2002 State of the Union address, he made a request that he repeated on the warm South Lawn on Monday: each person should serve about two years of their lives helping neighbors in need.

The president said that's a lot to give over the course of a lifetime, but that those who do it end up as enriched as those they help.

He also reminded people of a point he made in his first inaugural address in 2001 — that Americans should be "citizens, not spectators."