By Nellie Andreeva

LOS ANGELES (Hollywood Reporter) - With the broadcast networks' "upfront" presentations to advertisers less than a month away, it's do-or-die time for "bubble" series, those modestly rated shows walking a fine line between renewal or cancellation.

Not all shows that haven't been renewed yet are in jeopardy: For such series as CBS' "How I Met Your Mother," which traditionally gets picked up at the last minute, and ABC's "Ugly Betty," the orders are just a formality.

But that can't be said for a dozen or so other series anxiously awaiting their fate.

CBS has the most, including a quartet of long-running procedurals -- "Without a Trace," "Cold Case," "Numbers" and "The Unit" -- along with freshman drama "Eleventh Hour."

For all of them -- especially the two oldest, "Trace" and "Case" -- the decision is tied to the shows' economics, as the network pays most or all of the production costs at this point.

The odds for "Trace" and "Case" are considered 50/50 right now, with one of the two expected to come back.

"Numbers" looks good to return for a sixth season, as does its Friday-night companion, "Ghost Whisperer," which would enter its fifth cycle.

The prospects for "Eleventh Hour," meanwhile, do not look good. The military drama "Unit" also had been considered unlikely to come back, but in a hopeful sign, executive producer Shawn Ryan has been asked by the network to present ideas for a fifth season.

Of Fox's two bubble series, "Terminator: The Sarah Connor Chronicles" and "Dollhouse," sophomore "Terminator" is considered all but gone, while freshman "Dollhouse's" chances are 50/50.

Along with Fox's sci-fi duo, the most discussed bubble show online is NBC's "Chuck," which finally showed a ratings uptick this past week but is still performing marginally despite a strong fan base. The dramedy's chances also have been hurt by the promising start of NBC's police drama "Southland," as the network will have only few hourlong slots in the fall when Jay Leno takes over the 10 p.m. hour every night.

Another NBC Monday series, the modestly rated but reliable procedural "Medium," is said to have slightly better odds to return than "Chuck," while the quirky cop drama "Life" is expected to join "Kath & Kim" on cancellation row.

Meanwhile, the original "Law & Order" series is expected to return for a record-tying 20th season, matching the run of "Gunsmoke," though its order will probably not be for a full 22-episode season.

Neither of ABC's midseason entries have broken through, but while "Cupid" has been pretty much written off, the comedy "Better Off Ted" and the dramas "The Unusuals" and "Castle" are still in consideration as ABC brass is said to be happy with the them creatively.

"Unusuals" has a major test this week: To boost its chances, the network has scheduled a second original episode of the show after the "Dancing With the Stars" results show in addition to its already prominent regular airing after "Lost."

Over at the CW, "Reaper" is gone, while the prospects for "Privileged" have improved, and the show is now considered for a possible midseason order.

(Editing by Dean Gooodman at Reuters)