NEW YORK (AP) - HBO has bought the U.S. rights to a behind-the-scenes documentary on Barack Obama's presidential campaign from actor Edward Norton's production company.

Filming will continue through the president-elect's inauguration, with the premiere expected sometime in the spring, the network said Friday. HBO reportedly paid at least $1 million to show the still-untitled film.

Director Amy Rice, working for Norton's Class 5 Films, had contacted Obama about a potential documentary even before he decided to run for president, HBO said. When Obama started his campaign and it became a success, Rice and fellow director Alicia Sams found themselves in the right place at the right time.

Over 2½ years, the filmmakers had "unprecedented" access to the candidate, his family, friend and campaign volunteers, HBO said. Sam Pollard, editor of HBO's "When the Levees Broke," has been hired as film editor.

© 2008 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.