Red Bull is not ruling out any options for an engine supply deal next year after the latest round of speculation linked the team to Honda for 2016.
Red Bull's decision earlier this year to cut its ties with current engine supplier Renault has led to a very public search for a replacement, in which it has been turned down by Mercedes and Ferrari. At the last round in Russia, there was speculation Red Bull might patch up its differences with Renault, but no solid progress has been made public on that front in the last two weeks.
Honda, which has struggled to get up to speed in its first year back in F1 as McLaren's supplier, ruled itself out of offering engines to a second team earlier this year, but with options looking increasingly slim for Red Bull, the latest rumours suggest the Japanese manufacturer may have had a change of heart now development has opened up for next year. Although such a scenario still seems unlikely and would require the blessing of McLaren, Horner is not willing to rule out any scenario at this stage.
"Well so far we've had the rumour of every single engine mentioned in the back of our car for next year, so they probably have a 25% chance if you look at it that way," he told Sky Sports. "There is so much speculation, a lot of opinion is being based on it, so when we have something to say and something is fixed ... it is being worked on very hard at the moment."
But despite the urgency, Horner said it is unlikely the situation would be resolved in the coming week.
"It'll be November next week then suddenly it is Christmas and then testing starts," he said. "We need to get something sorted over the next couple of weeks. It would be nice to have everything firmed up by the time we leave Mexico, but the likelihood of having it by then is unlikely."