CBS has led among households and total viewers for years, but when it comes to buzz, the top-rated network ranks dead last, behind even ratings-challenged NBC.

CBS hopes to change that this fall with a group of edgy new shows, likely including one featuring singing and dancing gamblers and another about a group of ‘70s swingers. 

The network seems likely to have at least five new shows and perhaps a timeslot switch for one of the fading “CSI” spinoffs when it announces its fall schedule to media buyers tomorrow, the most changes in recent years. Last fall the network debuted just four shows.

It's also a huge departure from a schedule long dominated by police procedurals.

“CBS is looking to extend its reach to wider audiences by offering a mix of genres and programs that will generate watercooler buzz,” says a pre-upfront report from Carat, the giant media buying agency.

CBS needs to do something. In the past three years, it has not launched a new show that ranked in the top 10 in adults 18-49. ABC, NBC and Fox all have.

Further, CBS’s 18-49 season average is down 3 percent from last year, from a 3.8 to a 3.7, despite the fact that it carried the Super Bowl this year. In women 18-49, a group highly coveted by advertisers, its average has fallen 7 percent, from a 4.4 to a 4.1.

“The network continues to have difficulty with launching successful new character-driven dramas and comedies, and remains over dependent on crime procedurals,” notes the Carat report.

Among the shows CBS is expected to unveil tomorrow are “Viva Laughlin,” from executive producer Hugh Jackman, a musical mystery based on BBC’s “Viva Blackpool,” and “Swingtown,” which follows a group of wife-swappers in 1970s suburbia.

Also tentatively on schedule: “Babylon Fields,” featuring a group of zombies in a small New York town, and “Cane,” starring Jimmy Smits as the heir to the family rum trade who runs up against some steamy rivals.

In addition, CBS will pick up at least one new comedy.

Among the shows not expected to return in the fall are three second-year shows: “The Unit,” “Close to Home” and “How I Met Your Mother,” though the last could return at midseason.

Also on the expected X list: the apocalypse drama “Jericho,” whose ratings went into free fall after a decent start.

As for nights of the week, media people speculate that Monday will remain mostly the same, with “The New Adventures of Old Christine” sharing the 8 p.m. hour with a new comedy, “Two and a Half Men” and “Rules of Engagement” returning at 9, and “CSI: Miami” at 10.

Tuesday could see a big change, with “CSI: NY” possibly taking over the 9 or 10 timeslot and a new drama joining current 8 p.m. occupant “NCIS.” CBS has had a half-dozen shows at 10 p.m. the past two years, and none has made it more than a few months. Thursday’s “Shark” is also a contender for the timeslots.

Wednesday will see at least one and possibly two new dramas, if “CSI: NY” moves to Tuesdays, to pair with current 9 p.m. show “Criminal Minds.” Though there have been rumors that “Survivor” will move to Wednesday, several media researchers said late last week that they don’t believe it.

Thursday’s first two hours will thus stay the same, and 10 p.m. will go to the network’s most promising new drama, perhaps the Smits show.

“Shark” will probably move to Friday at 9 p.m., replacing “Home.” “Ghost Whisperer” will stay at 8 and “Numb3rs” at 10.

Saturdays will be “48 Hours Mystery” and crime show repeats.

Sunday could be the only day without any adjustments, as it was the only night where CBS gained this season. The lineup includes “60 Minutes,” “The Amazing Race,” “Cold Case” and “Without a Trace.”