WASHINGTON (AP) -- Aretha Franklin will sing, the Rev. Rick Warren will pray and more than 11,000 U.S. troops will be watching over inauguration ceremonies in case of an attack during President-elect Barack Obama's swearing-in on Jan. 20.
As many as 4 million visitors are expected to be on hand when Obama takes the noontime oath from Chief Justice John Roberts on the steps of the Capitol.
Some 4,000 local police, 4,000 police from around the country and security agents from other government agencies will be on hand, taking direction from the Secret Service. About 7,500 active duty military and 4,000 National Guard troops also will participate. That includes a contingent on alert to respond to a chemical attack.
A "big chunk" of active and guard units will perform ceremonial work involving parades, reviews and honor guards, the U.S. commander in charge of domestic defense said Wednesday.
Planners are working under the assumption a terrorist or rogue element might try to interrupt the event, said Gen. Gene Renuart, head of the U.S. Northern Command. "So it's prudent for us to plan for the possibility of that kind of event, and to be prepared either to deter it or to respond to it," he said in a session with defense writers.
Also Wednesday, officials announced the list of participants for the inauguration.
The program is to feature poet Elizabeth Alexander; the Rev. Joseph Lowery, a veteran civil rights leader; the U.S. Marine and Navy bands; and the San Francisco Boys Chorus and the San Francisco Girls Chorus.
"So it's prudent for us to plan for the possibility of that kind of event, and to be prepared either to deter it or to respond to it," he said.
Sen. Dianne Feinstein, D-Calif., chairman of the Joint Congressional Committee on Inaugural Ceremonies, said the day would be "an event of historic proportion."
"It is appropriate that the program will include some of the world's most gifted artists from a wide range of backgrounds and genres," she said.
Cellist Yo-Yo Ma, violinist Itzhak Perlman, pianist Gabriela Montero and clarinetist Anthony McGill will perform a new work composed by John Williams, who also provided music for Obama's election night rally in Chicago's Grant Park. The committee did not release a title for the work by Williams, who is best known for his film scores such as "Star Wars" and "Jaws."
Others on the schedule were a nod to Obama's election as the country's first black president.
Franklin, a living legend with 21 Grammies, performed for President Bill Clinton in 1993, but this would be her first Inauguration. During a Labor Day weekend rally in Detroit, Obama sang a bit of Franklin's "Chain of Fools" to her.
She is only the fourth poet to have a speaking role at a presidential Inauguration. Robert Frost, who was 86 at the time, wrote a poem for Kennedy's inaugural in 1961 but couldn't make out the words of the poem in the sun's glare. Instead, he recited an earlier work. Clinton chose Maya Angelou to write a poem for his first inaugural in 1993, and Miller Williams read "Of History and Hope" at his second inaugural.
Liberal groups criticized the inclusion of Warren, whose "Purpose Driven Life" books and lectures have made his church among the largest in the country. People For the American Way President Kathryn Kolbert said Warren's support for California Proposition 8, which banned gay marriage, should have blocked his invitation.
A popular figure among evangelicals, Warren remained publicly neutral during the presidential campaign. He invited both Obama and his Republican rival John McCain to his Saddleback Church in Orange County for a forum on faith and public service.