Manor have said that their "plan A" is to keep Indonesian rookie Rio Haryanto on the team in 2016.
In Hungary, it emerged that alternatives like Stoffel Vandoorne and Jordan King are in the running because Haryanto's sponsorship had dried up mid-season.
"Plan A is to keep Rio on board for the remainder of the season, but we have other options," team chief Dave Ryan is quoted as saying by Dutch newspaper Algemeen Dagblad.
Haryanto has so far failed to pick up any points for Manor.
