Fox announced Wednesday it is no longer interested in airing the fourth installment of the comedy reality series “The Simple Life,” but NBC and The WB are said to be vying for the project, sources said.

The latest installment of “Life,” which once again stars socialites Paris Hilton and Nicole Richie and is currently in preproduction, was initially going to focus on preparations Ms. Hilton and Ms. Richie were making for their respective weddings, but the show’s theme was thrown into question after Ms. Hilton broke off her engagement. A public falling out between Ms. Hilton and Ms. Richie has been reported for months in tabloids and on the Internet.

A statement issued by Fox said the network was dropping the show because of scheduling reasons.

“We have a unique midseason situation,” the statement said. “In January we have to accommodate 2½ hours of new programming with ’24’ and ‘American Idol.’ We also have completed episodes of both scripted and unscripted series in the wings … collectively; we did not see a place for ‘The Simple Life’ on our schedule this season.”

The studio producing “Life,” 20th Century Fox Television, also made a statement.

“We’re disappointed that ‘The Simple’ Life will not continue on Fox, where it has performed so well, but we believe this series starring Paris Hilton and Nicole Richie is still a dynamic and valuable franchise,” the statement said. “We hope to be able to announce a new network partner in the coming days.”

Jon Murray, the executive producer of “Life” and the chairman and president of Bunim-Murray Productions, which produces the series along with 20th, said in a statement the Fox announcement was a temporary setback.

“We have a hit series with 18 to 49 year olds starring two of the most written about women in the world,” Mr. Murray said. “We’re very excited about the creative plans for the next group of episodes, and are confident this situation will be remedied quickly.”

The show is slated to begin production in November and is expected to be ready for a January launch. “Life” will still be marriage-themed, and the production has taken into account the personality differences between Ms. Hilton and Ms. Richie, sources said.