The Nissan e.dams Formula E squad has been contacted by "15-20" drivers about a possible seat for the 2018/19 season, according to team boss Jean-Paul Driot.
Nissan had been expected to field Sebastien Buemi and Alexander Albon in its first FE season since taking the e.dams entry over from alliance partner Renault.
But with Albon - signed to a three-year FE contract in July - now closing on a 2019 Toro Rosso Formula 1 seat, Nissan is likely to need a new driver to slot in alongside 2015/16 champion Buemi.
When asked if Nissan was looking for a replacement for Albon as it negotiates his Red Bull situation, Driot told Autosport: "We are - we had so many drivers who rang during these two days, I couldn't believe it.
"Drivers who rang, who sent emails - if I give you the names you are going to be very astonished - incredible.
"I think at least 15-20 [got in contact]."
Nissan replaced Albon for the final day of last week's Valencia pre-season test with former DAMS Formula 2 racer Oliver Rowland.
Driot confirmed 2015 Formula Renault 3.5 champion Rowland is in contention for the race seat.
"Oliver is in consideration because we were thinking about him for the third driver anyway, and we know him well because he did Formula 2 with us the same year as [Charles] Leclerc was racing in Formula 2 [in 2017]," he said.
"And he did well - he won three races and did poles - and we know him because he was in Renault 3.5."
Rowland completed 85 laps for Nissan on the third day of the test, including a 21-lap run that was the team's longest stint of the week.
"It was good - I just focused on race stuff," Rowland explained to Autosport.
"It was fine, I got my head around that a little bit and just worked through the programme for the guys and Nissan really.
"It was nice to get out in the wet - seemed pretty competitive. I didn't really do any performance running in the [dry] afternoon, but it was good.
"It's really hard for me say [where Nissan is in FE's competitive order], I haven't been involved in any of the [private] tests.
"But the pace seemed quite good - I don't even know who is the best to compare to or anything like that.
"But it was important for me to just try and understand as best I can with the car and also just give them the data and stuff they need."
Regarding the possibility of racing for Nissan in FE in season five, Rowland, said: "Obviously I came here and covered - super-subbed - for them again, a bit like I did with Nicholas Latifi at the start of the year [in F2 testing].
"But let's see - obviously I'd like to race in Formula E, so we'll see what they come up with."