Both Action Express Racing and Wayne Taylor Racing have been forced to revert to backup plans to fill its third driver seats at the Mobil 1 Twelve Hours of Sebring, with Toyota electing not to release its LMP1 drivers for the race.

Mike Conway, and either fellow Toyota Gazoo Racing teammates Fernando Alonso or Kamui Kobayashi had initially been anticipated to complete the lineups in the No. 5 Action Express Cadillac DPi-V.R and No. 10 Wayne Taylor Racing Cadillac DPi, respectively, although have been ruled out due to the FIA World Endurance Championship round at Sebring that weekend.

A Toyota spokesperson confirmed to Sportscar365 that its drivers will be focused exclusively on the 1000 Miles of Sebring race, which takes place the evening prior to the 12-hour IMSA enduro.

“We thought we had this covered but clearly we can’t expect those two guys to come to us when they’re running Toyotas,” Wayne Taylor told Sportscar365.

“In the beginning, we thought there was a chance. Now there’s no chance.”

Taylor said he’s close to finalizing a replacement driver for Sebring that will join full-season drivers Jordan Taylor and Renger van der Zande behind the wheel of the Konica Minolta-sponsored Cadillac DPi.

“We are negotiations with a third driver,” he said. “I’ll only know [next week] because of his commitments now.”

Action Express team manager Gary Nelson, meanwhile, said they have two different options on the table for its No. 5 entry, alongside Filipe Albuquerque and Joao Barbosa, with a decision likely to be made following the Rolex 24.

“We’ve talked to a couple of guys and they’re both ready,” Nelson told Sportscar365. “But the conversation was if Conway can’t do it, are they available?”

Nelson confirmed that Conway will return to the team for the final two Michelin Endurance Cup races of the season at Watkins Glen International and Michelin Road Atlanta, which has since seen a clash with the Fuji WEC round avoided.

The identity of WTR’s third driver for the two other races, meanwhile, remains unclear.

Multiple Drivers Expected to Pull Sebring Double Duty

Upwards of a dozen drivers could end up contesting both the WEC and IMSA races, with several already confirmed to complete the unique first-ever Sebring double.

Ford Chip Ganassi Racing WEC drivers Olivier Pla and Harry Tincknell will also take part in the IMSA race with the Multimatic-supported Team Joest operation, while WEC LMP2 points leader Gabriele Aubry of Jackie Chan DC Racing is set for a full WeatherTech Championship season with PR1/Mathiasen Motorsports.

WTR’s van der Zande, meanwhile, will also take part in the WEC race with DragonSpeed and WEC GTE-Am points leader Patrick Lindsey splitting time between two Porsches, while factory drivers from BMW, Ferrari and Porsche could also pull the double.

Sportscar365 understands that Corvette Racing, which is tipped to enter a solo Corvette C7.R in the 1,000-mile WEC round, could also utilize two of its IMSA drivers.