With IMSA opening up entrant registration for the 2015 TUDOR United SportsCar Championship, November is set to be a busy and crucial month for teams working to finalize programs for the upcoming year.

While car counts in Prototype Challenge and GT Le Mans have stabilized, with no significant changes other than the withdrawal of SRT’s Dodge Viper program, both the Prototype and GT Daytona classes could see noticeably smaller full-season grids in 2015, based on current projections.

The Prototype class could face as much as a 40 percent drop in full-season entries compared to the start of 2014, with only eight P class cars having been confirmed for the entire 2015 season. It includes the recently announced Michael Shank Racing Ligier JS P2, which will debut at the Twelve Hours of Sebring in March.

Action Express (2 Corvette DPs). Wayne Taylor Racing (Corvette DP), Spirit of Daytona Racing (Corvette DP), Chip Ganassi Racing (Riley-Ford DP) and SpeedSource (2 Mazda P2s) have also confirmed their participation, although some question marks exist over any additional full-time entries.

After missing the season-ending Petit Le Mans to instead compete in the FIA WEC race in Shanghai, Extreme Speed Motorsports is expected to only mount a limited North American program with its new HPD ARX-04b cars, likely tied around the opening two races of the season, while the DeltaWing is also not expected to contest the entire 10-round championship.

Plans for a Riley-Dinan DP under the Rahal Letterman Lanigan banner has fallen through, according to team principal Bobby Rahal, while prospects of seeing 8Star Motorsports with a P2 car is dwindling, as the Enzo Potolicchio-owned team focuses on filling its two PC cars instead.

Starworks Motorsport, another team that was poised to step up with HPD’s new P2 car, has yet to finalize any sort of program for next year, although options in DP and PC are also being explored.

RSR Racing, meanwhile, will focus its North American efforts on Prototype Challenge, much as could end up being the case for 8Star and Starworks in opting for the more affordable spec prototype class instead.

One holdout could be OAK Racing, which is expected to take part in the opening two rounds with its Ligier JS P2 Honda, and could mount a full-season program if it finds the necessary funding.

Additional entries, however, are expected for the Tequila Patron North American Endurance Cup races, including Krohn Racing’s Ligier JS P2 Judd and the possibility of a second Ganassi Riley-Ford and third Action Express Corvette DP.

The GTD class is expected to take the biggest entry hit, with no more than seven cars confirmed out of the 25 registered full-season entrants from 2014, including a handful of teams departing for Pirelli World Challenge.

Alex Job Racing (2 Porsches), Scuderia Corsa (Ferrari), Paul Miller Racing (Audi), TRG-AMR (Aston Martin), Riley Motorsports (Dodge Viper), and Park Place/Horton (Porsche) are all either confirmed or likely entrants at this point, along with the strong possibility of GB Autosport and Magnus Racing as well, which would bring the class up to 9 or 10 full-season cars.

The rest is all a bit unclear at this stage, with reigning class champions Turner Motorsport and NGT Motorsport departing for World Challenge. They could soon be followed by Flying Lizard Motorsports, which has yet to announce its 2015 plans.

Dempsey Racing’s U.S. program is in jeopardy, after the majority of the Georgia-based staff was laid off last month, including its team manager Greg Cates, while Fall-Line Motorsports is expected to concentrate on its Continental Tire SportsCar Challenge program.

Muehlner Motorsports will only commit if they find funded full-season drivers by the end of this month and Patron Endurance Cup champions AIM Autosport are working to put together a program following Bill Sweedler’s departure, but may only end up being for a partial season.

While possibilities exist for Magnus, Scuderia Corsa, TRG, Riley and Park Place to run second cars, most could be looking at Patron Endurance Cup-only programs for its additional machinery.

Car counts are expected to remain relatively unchanged in the PC and GTLM classes, with the spec prototypes potentially seeing a slight increase, should some of the team’s P class programs fail to materialize.

GTLM, meanwhile, could drop into the high single-digits at some races, thanks to SRT’s withdrawal. It’s understood the Viper SRT GTS-Rs are being returned to Chrysler in Detroit and will not likely be in the hands of customers.

IMSA has yet to reveal any potential class limits, as enforced in 2014, and will likely wait until the entry deadline of Dec. 1 before determining any potential car caps.