Schmidt Peterson Motorsports says Le Mans 24 Hours winner Brendon Hartley and Robert Wickens are part of a 28-driver list to race the team's second full-time IndyCar entry in 2018.
Mikhail Aleshin left the team to help develop BR Engineering's Dallara-built LMP1 car last month, and the vacancy at Schmidt Peterson has become a key part of off-season driver moves.
Sebastian Saavedra and two-time Indy Lights runner-up Jack Harvey have raced the car since Aleshin's departure and DTM driver Wickens is said to be keen on the seat, with all three drivers on the shortlist.
Mercedes' impending departure from the DTM and Porsche's exit from LMP1 in the World Endurance Championship, both in favour of Formula E efforts, has given SPM reason to look outside of the US for new drivers.
"We had a conference call this week, with a spreadsheet of 28 drivers," said team co-owner Sam Schmidt.
"Pretty much everyone who raced in IndyCar this year and who isn't already signed was on the spreadsheet, but we're also looking to Europe and wondering if we should wait to see what happens in the Formula 1 ranks.
"But it's no secret that we're interested in all the guys getting pitched out of LMP1 rides and DTM rides this year and next year.
"In theory some of them have their futures secured.
"Real strong talents like Brendon Hartley, Robert Wickens, Earl Bamber - I think they all have strong cases for trying to make it in IndyCar.
"They could all do a good job."
Schmidt admitted the search for Aleshin's replacement had distracted the team from finalising current driver James Hinchcliffe's contract extension, but said a deal was close.
"We've been focused mostly on trying to find a competitive and complementary driver to go with James," added Schmidt.
"But then I woke up and thought, 'Actually, first we need to make sure we get James to re-up'.
"I'm pretty confident that will get done soon, because I think it's in everyone's best interests to renew the contract and maintain continuity."
Schmidt also added that it was unlikely the team would expand to running three cars.