Red Bull Racing say they are happy to wait for Daniel Ricciardo to make up his mind on his Formula 1 future.
Ricciardo's long-term deal comes to an end after 2018, and Ricciardo is rumoured to be a target from both Mercedes and Ferrari.
However, Red Bull are keen to hold onto the Australian as Max Verstappen's team-mate.
Ricciardo has won five races and finished on the podium 27 times with the team, but wants a car capable of winning a World Championship.
“The next move he makes at 28 years of age is a very important one for him. So of course I’m sure he’s going to take the time to make sure the decision is right for him,” said Red Bull team boss Horner.
“But he knows the intent very clearly, and I’ve discussed it with him, is that we want him in the team. If that takes another six months, then so be it.”
Red Bull have endured a few reliability issues in 2017, with Ricciardo forced to retire from the last two Grand Prix. Verstappen has also had multiple DNF's this season, keeping Ricciardo cautious.
“I think he’s keen to see what engine performance looks like next year, which is understandable,” said Horner.
“He knows how we go about our racing and how we treat the two drivers, which he’s extremely comfortable and happy with.
“I think, as his character has developed and as his personality has come across, he sees the fit between Daniel Ricciardo and Red Bull.
“I think he sees the capability that we have within the team. And I think he’s very happy in the team.”