Although the cost of the inaugural is as yet unclear, Linda Douglass, a spokeswoman for the committee, said Mr. Obama expected to incur expenses that past presidents had not, because he wanted to make as many events as possible accessible to the public.

Image President Bush at the end of his 2005 inaugural address. A far bigger crowd is expected at the inauguration of Barack Obama, whose planners on Tuesday announced restrictions on donors. Credit... Stephen Crowley/The New York Times

“We’re going to explore all kinds of creative ways to open this up to the public, everything from the swearing-in to the events,” Ms. Douglass said, adding that the celebration would include activities elsewhere in the country.

“This inauguration is more than just a celebration of an election,” she said. “This is an event that can be used to inspire and galvanize the public to act. That is what we’re aiming for.”

The committee is also working with federal officials to open to those attending the inauguration as much as possible of the Mall, which stretches two miles from the Capitol to the Lincoln Memorial. The section east of the Washington Monument has traditionally been used as a staging area for marching bands and others who participate in the inaugural parade, but they may be moved elsewhere this time to accommodate the crowds, most of whom will have to view the swearing-in ceremony and the parade on JumboTron screens.

In modern times, inaugurations have been financed by a combination of public and private money. Most recently, in 2005, Mr. Bush spent a record $42.3 million on his inaugural events, most of it collected from corporations and executives. That money was directed mostly toward festivities, including fireworks, inaugural balls, the parade and a concert on the Mall.

But the federal and District of Columbia governments also spent a combined $115.5 million, most of it for security, the swearing-in ceremony and cleanup; the biggest expense by far, $84 million, was to compensate federal workers for the holiday.

In barring lobbyists from contributing, Mr. Obama is continuing a practice he began with his campaign and applied as well to his transition, in which contribution limits are $5,000.