Mercedes are still undecided on who will replace Nico Rosberg alongside Lewis Hamilton for 2017, with non-executive director Niki Lauda confirming "difficult" discussions could see the decision delayed until the end of January.
The chamionship-winning team are desperately seeking a replacement for the retiring world champion and were caught off guard by his surprise announcement just five days after winning the title.
Lauda admitted he was angered by Rosberg's decision and the lack of notice which he says has left Mercedes looking "stupid".
Speaking to Austria's Servus TV, Lauda admitted they've yet to land on a final decision and continue to weigh up different options, including promoting junior Pascal Wehrlein, or pushing for an experienced driver like Valtteri Bottas.
"We had hoped for a quickest solution, but the discussions are proving to be difficult," said the Austrian.
"There are two scenarios – we take a young gun like Wehrlein who could turn out to be a Verstappen, or we take an experienced guy.
"But we are still making up our minds. That's a huge discussion, really. It could take us until the end of January until we know which scenario we are going to take."
Red Bull's Helmut Marko, who was sat beside Lauda during the interview, believes they should take Wehrlein as not doing so would diminish their young driver programme.
"You have a young driver programme and you have the highly-rated Wehrlein," he added. "But according to our information it won't be Wehrlein in the car. This means you don't trust your own junior programme."
