New York ? Fox executives promised to boost a sagging “American Idol” as they confidently outlined plans on Monday for a new season and declared the network the one that “delivers America’s favorite shows.”

Fox is making a special effort to establish new comedies next season, introducing shows that feature Keri Russell and Cloris Leachman. Its big-ticket drama is a fantasy adventure series from Steven Spielberg, although executives conceded there’s a chance it won’t be ready next season.

Fox’s most compelling mystery for next season remains: Who will replace Simon Cowell when he leaves “American Idol” this month?

That search is top priority for Fox this summer, said Peter Rice, entertainment chairman of the Fox Networks Group.

While it’s still television’s favorite show, “American Idol” has seen its ratings drop by 8 percent this season, according to the Nielsen Co. In response to viewer requests for more performances, Fox will increase the Tuesday night competition show from an hour to 90 minutes. The Wednesday results show will be chopped in half to 30 minutes.

Fox is giving extra attention to “Glee” in its second season, even though fans will get a scheduling challenge. A special episode of the show will get the prime post-Super Bowl time slot next season.

“Glee” will air Tuesdays at 7 p.m. Central time in the fall, ahead of two new comedies. After the Super Bowl, it will switch to Wednesdays at 8 p.m., following the “American Idol” results show.